If you try to delete all the files and folders inside the Windows "Temp" folder (located at %temp%), you might end-up encountering a few files which cannot be deleted as they are being used by some open Windows application or user. The solution for this is to use an file-unlocker utility like "Unlocker" to disable all file-open handles and delete it. However there are some "invincible" files which will recreate even after forceful deletion. One such file is FXSAPIDebugLogFile.txt, luckily it's no malware and just a log file associated to Windows Print and Document Services - and if you don't use Windows printer and fax network sharing features, can be safely disabled as shown ahead.

If you are unable to save files in Microsoft Office 2007 specially when exporting to PDF receiving error "This file is in use by another application or user" the solution is pretty simple and that is to disable your anti-virus and then save the file.