In theory, the items in the temp folder should be transient. In practice, it would be difficult to say for certain, but you can do some things to check if the file can be removed.
Search for the filename in the registry and see if you turn any hits up. If so, what are they? Consider using Sysinternals' Process Explorerto see if any process has a handle to that file. Also consider using Sysinternals Process Monitorto see if any application attempts to access that file. If it looks like the file is unused, consider renaming it and seeing how thing work for a while. If you don't experience any problems after a while, it is probably safe to remove.