Defrag, try a different drive, turn all virus stuff off (if you can without risk) try a different camera to capture with, most of this is above. You should hit the issue, and it never hurts to hollar at Sony.

Regards

The following is a disk speed test, available for free.

http://www.benchmarkhq.ru/english.html?/be_hdd.html (Scroll down to "Disk Bench" and click on Homepage)

Personally, I have not tested the above program, but it seems that it fits your needs.

Other performance analayzers are available here:

http://www.benchmarkhq.ru/english.html?/be_hdd.html

My dropped frame problems so far have always been fixed by defragmenting. I have a 300 GB internal drive in an external case / adapter, connected USB2 (firewire doesn't work for some reason.) Mysteriously to me, according to the Windows XP defrag analyze bar graph, the hard drive filled in the middle first. Although I had 100GB on either side, it was still bogging down and trying to fill all the nooks and crannies in the middle before accessing the rest of the drive, dropping frames in the mean time. Defragging packed everything in the middle like it wanted, and the rest went smoothly. Defragging has become a regular past time now, with no more issues. It was driving me nuts during the experience though, concerned I needed to send the camera in for re-aligning. Whew!