None of the solutions to similar problems I've read seems to apply to me:
I use my PC for general purpose, but also to record and watch TV which is when this problem occurs: Every 5 or 10 minutes the Disk Activity goes to 100% and the Disk Queue Length goes to 10 - 40ms, but with very little data transfer taking place (often <1MB/s) and low CPU usage. This causes whatever video I'm watching (and everything else) to freeze. Disk Activity stays at 100% for about a minute, then goes back to working normally and everything is fine. See screen capture of Resource Monitor below.
I've run Crystal Disk Info (see screen cap) and HD Tune, and they both report that everything is okay.
OS: Windows 7 64-bit pro
HDD: 500GB WD Caviar Green WD5000AADS as my only internal drive.
Motherboard: Gigabyte GA-MA785GM-US2H
CPU: AMD Athlon II X2 240
Memory: Kingston DDR2 800MHz 2GB