CaliforniaRN,
Thanks for the compliment! It's a nice change from people posting that I sound like a broken record~
iTunes updates the playcount in the iTunes Music Library.xml file at the end of each song that is played.
From what I see in Windows Explorer, it creates a temp file named IT.tmp and then when it finishes its playcount update in IT.tmp, it deletes the current XML file and renames the temp file to iTunes Music Library.xml. This is a reverse-engineering guess.
Also, I have some plug-ins always running that create files named temp and then get deleted....which is different than a normal iTunes installation. The plugin might be trying to use the XML file at the same iTUnes tries, and since there is a lock on the file, iTunes can't do it's delete/rename thing.
If your case, if you are getting tmp files without using plugins, I suspect security software was doing a scan and a similar thing happened.
Yes, you can delete those .tmp files. Here is an article for Macs, but it applies to Windows as well. I have deleted those tmp files after closing iTunes, with no harm to my iTunes setup.
http://docs.info.apple.com/article.html?artnum=93043
As far as I can tell, deleting a purchased file from your iTunes library only changes the iTunes Lubrary.itl file, not the xml file.