Erratic system speed

[Dan Shield]

First of all, if I'm not in the right newsgroup my apologies. I didn't know
where to start.

I've got a Compaq Presario 5000T with a 1.5 GHz P4 and 256 Meg RAM. Several
months ago, java apps started experiencing episodes where the would stop
responding for several minutes, and then continue on, only to repeat the
behavior several minutes later.

I first ran the spyware/adware utilities, and nothing out of the ordinary
showed up. I finally decided to reinstall the base os (XP). Did that, and
immediately updated to SP2. Same problem. Updated audio and video drivers.
Same problem. Updated the BIOS. Same problem. Replaced the sound card.
Same problem.

Now the kicker. I rebooted with a bootable Linux distro, downloaded and
installed the latest java version, configured FireFox w/ the plugin, and ran
one of the offending java apps. SAME PROBLEM!

I installed PCMark04 to benchmark the system, and I keep getting
inconsistent
results. I seems that it isn't only java apps, but heavy throughput that
cause the
system to slow to a crawl for several minutes, and then continue on OK for a
short time before repeating the process.

It appears to be a hardware problem, since the OS and associated drivers are
completely different, but I have no idea what could be going on. In my
experience,
hardware problems usually result in crashes, and not simply system
slowdowns.
Has anyone seen this before, or have any ideas as to what could be going on?

Thanks,

Dan