jittery DVD video & sound

Hardware: Toshiba Tecra 8000 laptop Pentium II 196,080K total physical memory
Software : Windows 2000, PowerDVD

DVD player originally, (when my bro gave me the machine), worked fine; I added a antivirus, firewall, spyware blaster.

Now the DVD is jittery and sound cuts out--synchronous with the drive light coming on.

Task Manager shows 74,500K memory still available with DVD running; CPU usage, though, hovers around 98-100%; the graph spikes are truncated at the top. Processes shows DVD using 95+% of the CPU.

There doesn't seem to be anything I can turn off to free up the CPU...

Any ideas about what caused the negative change, and how to resolve it?

 

Disable the antivirus and firewall while watching a DVD (and disconnect from the internet, for safety), since it worked better when it didn't have them.

 

The thing is, I've tried those options, with no effeect on improving the playback. confusing!

 

try updating your codecs

 

Codecs is the dvd decoder?