One solution for slowing down DVD burner
 

If your dvd or cd burner has slowed down in the burning process, try this. Go to control panel/system information/device manager and check out properties of the IDE section. Go to advanced settings to make sure that everything is DMA. If you find a setting with PIO, uninstall it, restart your computer. Your computer will reinstall it automatically and that should take care of it. If I made any mistakes in my explanation let me know.

I have no idea about that. Be careful not to break your computers, boys and girls :) Anyway my contribution to the topic is, be aware that the driver used by Daemon Tools and Alcohol 120% can slow down CD reading in some cases (I among many others verified it myself):

http://forum.imgburn.com/index.php?showtopic=11238
I have no idea if this might be related to your original tweak, of if your problem had another completely different cause. This driver can be cleanly un-installed with the original installer program.

There was a great program once, CD Throttle, which could set constant speed for a CD/DVD drive, so it would be staying always slowed down (good for CD music in games), or always on the high speed, for example.
I don't think it works still as well with modern drives and systems newer than WinXP, if at all. Won't work with Blu-Ray drives for sure.

Oh, very-very common issue in times of Win98 and XP for me. Not because this Windowses are buggy, but because interaction between Windows and "Starforce" disc protection overpopular in Russia at this times. See, it make itself middle layer driver between core and "true" CD/DVD drivers. And it rely upon "bad/weak" sectors. Everything is allright, until you'll encounter really bad CD. Sum of Starforce efforts to read it and Windows efforts to minimize problems ends in system falling back to safest - PIO - settings too frequent.

Moreover, seems, bugs in earlier Starforce drivers sometimes resulting in PIO settings for your HDD - and it's much worse than CD hassle! (Cure is the same - delete device and let Windows to re-found it for you).

Also, you don't need to reload whole system. Button "scan for new devices" will work it out. :)