Multiple profile files created
From MozillaZine Knowledge Base
Mozilla applications need to write to certain files in the profile folder. When those files are read-only or locked, you may experience performance issues or other symptoms and multiple numbered copies of those files may be created. Symptoms include:
Read-only or locked files in the profile
If you look inside the profile folder for your Mozilla application, the contents will include files such as bookmarks.html, cookies.txt, prefs.js, mimeTypes.rdf, sessionstore.js (Firefox only), and other files and folders. You should not see multiple numbered copies of these files ("bookmarks-<n>.html", "cookies-<n>.txt" "prefs-<n>.js", "sessionstore-<n>.js", "mimeTypes-<n>.rdf" , etc., where <n> is a number). You should also not see any "<filename>.moztmp" files ("bookmarks.html.moztmp", "cookies.txt.moztmp" ,"prefs.js.moztmp", etc.) since these temporary files are normally cleared after file changes to the profile have been completed.
Multiple numbered copies and "<filename>.moztmp" files can be caused if files in the profile are (or were at one time) read-only or locked. For example, if "cookies.txt" is read-only or locked, then the "cookies.txt.moztmp" temporary file will also be read-only or locked and a cookies-1.txt file will be created. Additional write attempts will result in cookies-2.txt and so on. If you find these types of files in your profile folder, remove the "read-only" attributes, if found, and delete any multiple numbered copies.
Note: On Windows XP (and Vista?) bug 375778 changes read-only attributes to read-write in current Mozilla application profiles  . This should prevent future instances of multiple files being created in the profile when users manually set the read-only attribute or copy read-only files to the profile. If Windows XP or Vista users are still seeing multiple files created it could be caused by other software locking the files in the profile.
Spotlight indexing - Mac OS
Mac users experiencing this problem should disable Spotlight indexing for your profile folder using the Privacy tab in the Spotlight preference pane. Norton Antivirus can also cause this problem on a Mac.  Disabling Norton's Auto-Protect feature will solve it, but may leave your machine vulnerable to attack.
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