I am running a fresh install of Windows XP SP3 with a very minimal set of applications installed, but even so, my computer often bogs down to a crawl while it is furiously accessing the hard drive, lighting the disk activity light solid for a minute or more.
The problem is the worst directly after startup / logon, but it sometimes also happens when the computer has been sitting idle at the desktop screen saver for a long time and is "woken up" to launch an application. Since this is a fresh Windows installation and I haven't noticed any other suspicious behavior or seen any unexpected network activity in my router logs, I am fairly confident that it is not a malware / virus causing the problem.
The Task Manager is not effective for troubleshooting in this case because either the computer will be too unresponsive to actually get the Task Manager open when the disk light is solidly lit, or other times, the list of processes will show that nothing is using more than 2 or 3 percent CPU time, even though the computer is practically frozen up.
Are there any good tools out there (preferably free) that could help pinpoint the offending process(es)? Something similar to the Resource and Performance Monitor on Windows 7 might do the trick.