Computer keeps falling into PIO mode

Hello, I am on a Dell Inspiron e1505 running Windows XP sp2. Lately, my computer keeps repeatedly falling into PIO mode, as opposed to DMA, when "DMA if available" is the selected option. As far as I can tell, this is in some way correlated with me playing high quality streaming video for long periods of time, or apparently loud music for prolonged periods (this was how it first occurred).

Now, all I know about this problem is how to correct it when it occurs, which was told to me in this very forum. What I do is go into Device Manager, under IDE ATA/ATAPI controllers, and into the Properties window for the Primary IDE Channel. There, I go into Advanced Settings and toggle the Transfer Mode from "DMA if available" to "PIO only", and then back, and then restart my computer.

If that doesn't work (and, coincidently, it never has worked) I run RegEdit and (quoting from the last thread I had on this matter) "go to the following path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}\000X . The last four digits will be 0000, 0001, 0002, 0003, and so on. Click directly on each of the numbered folder/keys, then delete all occurrences of the following values on the right side.: MasterIdDataChecksum SlaveIdDataChecksum. Now reboot your system and make sure the DMA Mode has returned to the ?Current Transfer Mode? line."

After doing this, the problem is always fixed. Unfortunately, this doesn't stop it from occurring again, and again, and that is why I've come here for help.

Does anyone know anything that I could do to prevent this from happening repeatedly? Or why it might be happening over and over?

Thank you for your help.

PS. As a side note, I had some trouble previously with repeating appearances of the dreaded Windows blue screen and determined that it had something to do with overheating. I am a little hesitant to post this tidbit just because I'm not sure that was the actual cause, but by process of elimination it seemed that was the only possible reason left. Again, thanks to anyone who slogged through this post and might have some information to help...

--Chris