Laptop Hard Drive extremely slow, even in Seagate DOS disktest program

This laptop has been having occasional problems where it pretty much stalls on
anything. The last time, I finally found out that Microsoft Security Essentials
had somehow gotten turned on. (I use AVG AV and Zonealarm FW)

In the diagnostic process, I tried running the Seagate SeaTools DOS disk test
program. It runs extrememly slowly, maybe 1/10 the rate that the same drive,
tested on my desktop computer, runs. Eventually, run on the laptop (An HP
G60-125NR), the test times out and indicates an error (After hours). Running the
same drive on my desktop, it finishes with a Pass pretty quickly (maybe 1/2
hour). I have tried 3 different drives, and seen similar results with all 3.
Some months ago, it passed the test on the laptop, but took maybe a day and a
half to do it.

Does anyone have any idea what could be causing this, and is it repairable? Bios
setting? Motherboard defect? The battery does seem to be near its EOL, but still
will run it for 1/2 hour or more, and I do the test with the power supply on.

The computer still works most of the time, but it seems like this disk problem
could be seriously affecting the performance of the computer even when it does
seem to work.

If you can syggest a better group for this question, please do.