|I've deleted C:\Windows\Temp as a whole (directory + content) and I haven't seen any issue. I of course recreate the folder straight after deletion. Run deletion only if no major program is running, or before shutdown/reboot of machine.|
If you are not sure, move the entire contents of that folder, to another place (or make a backup on CD/DVD), and when you are sure you have a full copy, delete the folder. Then restart Windows.