Curcat,
Because I'm a rather lazy type I don't do the manual search for *.tmp, *.chk, *.whatever.
I just crank up a little prog called EASYCLEANER (find it with google) and let it sniff out all that crud.
So far I have not seen a problem with sending that stuff to the trash.
My "search" yielded me 25 files. Two of the files read as follows..."MSI1984.TMP-2C5C5FEA.pf" and "MSIB20.TMP-OD501DBD.pf". I went to C\Windows\Prefetch where they were located. In that folder, they are the only files that do not have .EXE somewhere in it's name. While these two files don't look like they belong there (not that I would know anyway!), I hesitate deleting a file that says it is a PF file. Is it ok to delete?
There was one other file (a config. setting), which read SL61.tmp.a5087c6d, that came up while searching for .tmp files. Is it ok to delete these files that have ".tmp" IN them? (using WinXP) Sorry for any confusion with duplication!

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