TEMP Files…

Running a W2K Server SP4 with SQL server, Apache, and other software. The TEMP directory is continuously filling up with files named TMPxxxx.tmp. Always the same format on the filenames – xxxx being numbers, always showing a 0 KB file size, and always in use by some program.
When I try to delete them I get a “sharing violation – file in use” error.

Does anybody know what is causing the generation of these files or how to determine what software is generating/using them?