Under normal circumstances it would change every ten minutes. After I had the first virus,(W32VBSKakworm), The disk contents changed every 30 seconds. This second worm,(W32Badtrans.B@mm). Even though I cleaned my computer of it, the disk contents keep changing every two minutes. The more often the disk contents change, the more difficult it is to run disk defragmenter and Scandisk.
I cuaght this worm on Thursday and immediately deleted it.