Just for kicks and grins, perhaps try uninstalling / unloading ANYDVD completely, then do an error check on the drive, delete any temp files, defrag then after the last reboot, try going into Device Manager and deleting first all your hard drives and optical drives, then your IDE controllers and reboot and let Windows XP re-discover them. Then you may want to try re-installing your motherboard chipset drivers and see what happens.
BTW, you may also want to try the RipIt4Me front end for DVD Decrypter to see if DVD Decrypter is at fault or if perhaps AnyDVD was.
Best of luck.
BTW, here is the text of another post to help you with RipIt4Me:
Okay. I downloaded the following files:
RipIt4Me Version 188.8.131.52 http://www.ripit4me.org/download.html
FixVTS Version 1.5 http://www.videohelp.com/~FixVTS/
and of course had the last version of DVD Decrypter (184.108.40.206) already installed.
All I did was place the small, self-contained RipIt4Me (409,600 bytes) and FixVTS (114,688 bytes) executables in the DVD Decrypter folder and from there, placed the DVD into the drive and closed the drive door (while holding down the shift key) and after the drive light was all done blinking, took my hand off the shift key and started the RipIt4Me app.
I followed the wizard, processed it with FixVTS when prompted and the disk was backed up successfully - no problem at all. Plays in my WinDVD app right off the hard drive without incident.
DVD Decrypter by itself was unable to rip the disk when I tried it.
So, I have an alternative, yet totally FREE, method of backing up more of my disks.