diff --git a/Classes/PHPExcel/CachedObjectStorage/APC.php b/Classes/PHPExcel/CachedObjectStorage/APC.php
index f6d974fe..56ae7f8b 100644
--- a/Classes/PHPExcel/CachedObjectStorage/APC.php
+++ b/Classes/PHPExcel/CachedObjectStorage/APC.php
@@ -46,7 +46,7 @@ class PHPExcel_CachedObjectStorage_APC extends PHPExcel_CachedObjectStorage_Cach
 
 			if (!apc_store($this->_cachePrefix.$this->_currentObjectID.'.cache',serialize($this->_currentObject),$this->_cacheTime)) {
 				$this->__destruct();
-				throw new Exception('Failed to store cell '.$cellID.' in APC');
+				throw new Exception('Failed to store cell '.$this->_currentObjectID.' in APC');
 			}
 			$this->_currentCellIsDirty = false;
 		}
@@ -94,7 +94,7 @@ class PHPExcel_CachedObjectStorage_APC extends PHPExcel_CachedObjectStorage_Cach
 			if ($success === false) {
 				//	Entry no longer exists in APC, so clear it from the cache array
 				parent::deleteCacheData($pCoord);
-				throw new Exception('Cell entry '.$cellID.' no longer exists in APC');
+				throw new Exception('Cell entry '.$pCoord.' no longer exists in APC');
 			}
 			return true;
 		}
@@ -121,7 +121,7 @@ class PHPExcel_CachedObjectStorage_APC extends PHPExcel_CachedObjectStorage_Cach
 			if ($obj === false) {
 				//	Entry no longer exists in APC, so clear it from the cache array
 				parent::deleteCacheData($pCoord);
-				throw new Exception('Cell entry '.$cellID.' no longer exists in APC');
+				throw new Exception('Cell entry '.$pCoord.' no longer exists in APC');
 			}
 		} else {
 			//	Return null if requested entry doesn't exist in cache
diff --git a/Classes/PHPExcel/CachedObjectStorage/DiscISAM.php b/Classes/PHPExcel/CachedObjectStorage/DiscISAM.php
index 84ffcc95..8a6f1508 100644
--- a/Classes/PHPExcel/CachedObjectStorage/DiscISAM.php
+++ b/Classes/PHPExcel/CachedObjectStorage/DiscISAM.php
@@ -38,6 +38,8 @@ class PHPExcel_CachedObjectStorage_DiscISAM extends PHPExcel_CachedObjectStorage
 	private $_fileName = null;
 	private $_fileHandle = null;
 
+	private $_cacheDirectory = NULL;
+
 
 	private function _storeData() {
 		if ($this->_currentCellIsDirty) {
@@ -116,7 +118,7 @@ class PHPExcel_CachedObjectStorage_DiscISAM extends PHPExcel_CachedObjectStorage
 		parent::copyCellCollection($parent);
 		//	Get a new id for the new file name
 		$baseUnique = $this->_getUniqueID();
-		$newFileName = PHPExcel_Shared_File::sys_get_temp_dir().'/PHPExcel.'.$baseUnique.'.cache';
+		$newFileName = $this->_cacheDirectory.'/PHPExcel.'.$baseUnique.'.cache';
 		//	Copy the existing cell cache file
 		copy ($this->_fileName,$newFileName);
 		$this->_fileName = $newFileName;
@@ -140,11 +142,15 @@ class PHPExcel_CachedObjectStorage_DiscISAM extends PHPExcel_CachedObjectStorage
 	}	//	function unsetWorksheetCells()
 
 
-	public function __construct(PHPExcel_Worksheet $parent) {
+	public function __construct(PHPExcel_Worksheet $parent, $arguments) {
+		$this->_cacheDirectory	= ((isset($arguments['dir'])) && ($arguments['dir'] !== NULL))
+									? $arguments['dir']
+									: PHPExcel_Shared_File::sys_get_temp_dir();
+
 		parent::__construct($parent);
 		if (is_null($this->_fileHandle)) {
 			$baseUnique = $this->_getUniqueID();
-			$this->_fileName = PHPExcel_Shared_File::sys_get_temp_dir().'/PHPExcel.'.$baseUnique.'.cache';
+			$this->_fileName = $this->_cacheDirectory.'/PHPExcel.'.$baseUnique.'.cache';
 			$this->_fileHandle = fopen($this->_fileName,'a+');
 		}
 	}	//	function __construct()
diff --git a/Classes/PHPExcel/CachedObjectStorage/Memcache.php b/Classes/PHPExcel/CachedObjectStorage/Memcache.php
index 28b74e39..4a134105 100644
--- a/Classes/PHPExcel/CachedObjectStorage/Memcache.php
+++ b/Classes/PHPExcel/CachedObjectStorage/Memcache.php
@@ -50,7 +50,7 @@ class PHPExcel_CachedObjectStorage_Memcache extends PHPExcel_CachedObjectStorage
 			if (!$this->_memcache->replace($this->_cachePrefix.$this->_currentObjectID.'.cache',$obj,NULL,$this->_cacheTime)) {
 				if (!$this->_memcache->add($this->_cachePrefix.$this->_currentObjectID.'.cache',$obj,NULL,$this->_cacheTime)) {
 					$this->__destruct();
-					throw new Exception('Failed to store cell '.$cellID.' in MemCache');
+					throw new Exception('Failed to store cell '.$this->_currentObjectID.' in MemCache');
 				}
 			}
 			$this->_currentCellIsDirty = false;
@@ -99,7 +99,7 @@ class PHPExcel_CachedObjectStorage_Memcache extends PHPExcel_CachedObjectStorage
 			if ($success === false) {
 				//	Entry no longer exists in Memcache, so clear it from the cache array
 				parent::deleteCacheData($pCoord);
-				throw new Exception('Cell entry '.$cellID.' no longer exists in MemCache');
+				throw new Exception('Cell entry '.$pCoord.' no longer exists in MemCache');
 			}
 			return true;
 		}
@@ -126,7 +126,7 @@ class PHPExcel_CachedObjectStorage_Memcache extends PHPExcel_CachedObjectStorage
 			if ($obj === false) {
 				//	Entry no longer exists in Memcache, so clear it from the cache array
 				parent::deleteCacheData($pCoord);
-				throw new Exception('Cell entry '.$cellID.' no longer exists in MemCache');
+				throw new Exception('Cell entry '.$pCoord.' no longer exists in MemCache');
 			}
 		} else {
 			//	Return null if requested entry doesn't exist in cache
diff --git a/Classes/PHPExcel/CachedObjectStorage/Wincache.php b/Classes/PHPExcel/CachedObjectStorage/Wincache.php
index 14435b13..93ce9549 100644
--- a/Classes/PHPExcel/CachedObjectStorage/Wincache.php
+++ b/Classes/PHPExcel/CachedObjectStorage/Wincache.php
@@ -48,12 +48,12 @@ class PHPExcel_CachedObjectStorage_Wincache extends PHPExcel_CachedObjectStorage
 			if (wincache_ucache_exists($this->_cachePrefix.$this->_currentObjectID.'.cache')) {
 				if (!wincache_ucache_set($this->_cachePrefix.$this->_currentObjectID.'.cache', $obj, $this->_cacheTime)) {
 					$this->__destruct();
-					throw new Exception('Failed to store cell '.$cellID.' in WinCache');
+					throw new Exception('Failed to store cell '.$this->_currentObjectID.' in WinCache');
 				}
 			} else {
 				if (!wincache_ucache_add($this->_cachePrefix.$this->_currentObjectID.'.cache', $obj, $this->_cacheTime)) {
 					$this->__destruct();
-					throw new Exception('Failed to store cell '.$cellID.' in WinCache');
+					throw new Exception('Failed to store cell '.$this->_currentObjectID.' in WinCache');
 				}
 			}
 			$this->_currentCellIsDirty = false;
@@ -103,7 +103,7 @@ class PHPExcel_CachedObjectStorage_Wincache extends PHPExcel_CachedObjectStorage
 			if ($success === false) {
 				//	Entry no longer exists in Wincache, so clear it from the cache array
 				parent::deleteCacheData($pCoord);
-				throw new Exception('Cell entry '.$cellID.' no longer exists in WinCache');
+				throw new Exception('Cell entry '.$pCoord.' no longer exists in WinCache');
 			}
 			return true;
 		}
@@ -132,7 +132,7 @@ class PHPExcel_CachedObjectStorage_Wincache extends PHPExcel_CachedObjectStorage
 			if ($success === false) {
 				//	Entry no longer exists in WinCache, so clear it from the cache array
 				parent::deleteCacheData($pCoord);
-				throw new Exception('Cell entry '.$cellID.' no longer exists in WinCache');
+				throw new Exception('Cell entry '.$pCoord.' no longer exists in WinCache');
 			}
 		} else {
 			//	Return null if requested entry doesn't exist in cache
diff --git a/Classes/PHPExcel/CachedObjectStorageFactory.php b/Classes/PHPExcel/CachedObjectStorageFactory.php
index d4c94797..cd402b23 100644
--- a/Classes/PHPExcel/CachedObjectStorageFactory.php
+++ b/Classes/PHPExcel/CachedObjectStorageFactory.php
@@ -37,7 +37,7 @@ class PHPExcel_CachedObjectStorageFactory {
 													),
 		self::cache_to_phpTemp				=> array( 'memoryCacheSize'	=> '1MB'
 													),
-		self::cache_to_discISAM				=> array(
+		self::cache_to_discISAM				=> array( 'dir'				=> NULL
 													),
 		self::cache_to_apc					=> array( 'cacheTime'		=> 600
 													),
diff --git a/Documentation/PHPExcel developer documentation.doc b/Documentation/PHPExcel developer documentation.doc
index 563ece1a..02b7839d 100644
Binary files a/Documentation/PHPExcel developer documentation.doc and b/Documentation/PHPExcel developer documentation.doc differ
diff --git a/changelog.txt b/changelog.txt
index ee582a8c..3015f5c4 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -39,8 +39,10 @@ Fixed in SVN:
 - Bugfix:   (MBaker) Work item 16246 - reader/CSV fails on this file
                      auto_detect_line_endings now set in CSV reader
 - Bugfix:   (MBaker) Work item 16212 - $arguments improperly used in CachedObjectStorage/PHPTemp.php
-- General:	(MBaker) Work item 15405 - Two easy to fix Issues concerning PHPExcel_Token_Stack (l10n/UC)
-- General:	(MBaker) Work item 15461 - Locale file paths not fit for windows
+- Bugfix:   (MBaker) Work item 16643 - Bug In Cache System (cell reference when throwing caching errors)
+- General:  (MBaker) Work item 15405 - Two easy to fix Issues concerning PHPExcel_Token_Stack (l10n/UC)
+- General:  (MBaker) Work item 15461 - Locale file paths not fit for windows
+- General:  (MBaker) Work item 16643 - Add file directory as a cache option for cache_to_discISAM
 
 
 2011-02-27 (v1.7.6):