When I run a refactor on my code in xcode, all the files are correctly refactored except one, and when I click to check the changes made in that file, the following 'Internal Error Occurs':

Uncaught Exception:
Invalid parameter not satisfying: fileName

Stack Backtrace:
The stack backtrace has been logged to the console.

Here is what it spat out in the console:

4/7/10 06:47:30  Xcode[35355] [MT] Uncaught Exception:
Invalid parameter not satisfying: fileName

Backtrace:
0  0x92842bbd __raiseError (in CoreFoundation)
1  0x914b9509 objc_exception_throw (in libobjc.A.dylib)
2  0x92842908 +[NSException raise:format:arguments:] (in CoreFoundation)
3  0x98801dc3 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] (in Foundation)
4  0x98db0f8e -[NSDocument(NSDeprecated) initWithContentsOfFile:ofType:] (in AppKit)
5  0x0075c07e -[PBXTextFileDocument initWithContentsOfFile:ofType:] (in DevToolsInterface)
6  0x007dc5be -[PBXFileDocument initWithFileReference:usingType:] (in DevToolsInterface)
7  0x00b1c0f8 -[XCRefactoringFileChangeSet(XCRefactoringModule_HelperMethods) referencedTextFileDocument] (in DevToolsInterface)
8  0x00b1d1f4 -[XCRefactoringEditableExistingTextFileChangeSet populateComparator:] (in DevToolsInterface)
9  0x00ab19b7 -[XCRefactoringModuleFileItem populateComparator:previewFinished:] (in DevToolsInterface)
10  0x00aa4606 -[XCRefactoringModule(MasterListDelegate) outlineViewSelectionDidChange:] (in DevToolsInterface)
11  0x987381cb _nsnote_callback (in Foundation)
12  0x927ca3f9 __CFXNotificationPost (in CoreFoundation)
13  0x927c9e2a _CFXNotificationPostNotification (in CoreFoundation)
14  0x9872d098 -[NSNotificationCenter postNotificationName:object:userInfo:] (in Foundation)
15  0x9873a475 -[NSNotificationCenter postNotificationName:object:] (in Foundation)
16  0x98af1de2 -[NSTableView _enableSelectionPostingAndPost] (in AppKit)
17  0x98bd11d0 -[NSTableView mouseDown:] (in AppKit)
18  0x98bcfeea -[NSOutlineView mouseDown:] (in AppKit)
19  0x007596c3 -[PBXExtendedOutlineView mouseDown:] (in DevToolsInterface)
20  0x98b6e548 -[NSWindow sendEvent:] (in AppKit)
21  0x00757a06 -[XCWindow sendEvent:] (in DevToolsInterface)
22  0x98a871af -[NSApplication sendEvent:] (in AppKit)
23  0x006f6dec -[PBXExtendedApplication sendEvent:] (in DevToolsInterface)
24  0x98a1ac4f -[NSApplication run] (in AppKit)
25  0x98a12c85 NSApplicationMain (in AppKit)
26  0x0000eee1
27  0x000021a5

If you would like to take a look at the project I'm working on, here is a link to download my xcodeproject: Tea Timer.zip

To recreate my problem, open Timer.h, attempt to refactor timeField to minuteField, use the preview function of refactor and then select Timer.m, to look at the changes supposedly made within. It will then raise this error without editing the file.