I see that on machines without SSD so let me share that I think it's Windows and other apps checking for updates, indexing and more. After awhile the performance returns.
I have a gen 2 80GB Intel SSD (with the latest firmware (late '09) as my boot drive on a custom built i7 Desktop. Normally this drive performs great, however, I have noticed from time to time (especially when the computer is turned on for the first time in weeks) that the drive can just hang for a few minutes. Is that just a common thing with SSDs that might happen? Is it common only to Intel SSDs?