my rule of thumb with temp files is to view details (no file menu, click vew/details)
click the heading over the dates to sort into date order, then select ALL .tmp files EXCEPT for todays dated files. then press the delete button.
sometimes it may not remove them, this is due to one or more files being in use. in this case, start at the bottom and select about 20 files and delete them, keep going till you are left with only a few files. (i am using Zone Alalrm pro and it uses the temp folder for its reference files, you cannot delete them.)