DVD+-R Drive Playback Problems

I have a Dell Inspiron 6400 with a DVD+-RW Drive (TS-L632D). Up until today it was reading discs perfectly fine. But then it started taking ridiculous amounts of time to copy files from a disc to my hdd. When I check the performance under windows task manager, the process was taking up at least 50% of my cpu. When I tried playing back a dvd movie, the playback was laggy. The same goes for other video files in several other discs. I flashed my drive with the update from Dell's support site, but the problem is still there. I also tried the above solutions in diagnostic mode. I know that the problem lies within the drive. Any suggestions to fixing this problem?

I'm thinking about going to buy a DVD Laser Lens Cleaner. What's the best one I can find?

 

Thanks, it works fine now. I did check DMA before for the primary IDE, but not the secondary. I'll sure to keep it in mind next time I run into this problem. Just out of curiosity, what might have caused it to go into PIO mode?