Updated iTunes and Quicktime... Big problems!
 

I am now running iPC. I updated to iTunes 8.1 and new quicktime. Now when I run them, my computer is unusable it's so slow. The mouse arrow will move a bit, then the system hangs and then it pops back up in another spot. I didn't have this problem with the original itunes/ quicktime

Hmm I had a problem like that when I updated my quicktime and itunes as well. What are your system specs? Do you have voodoo installed?

To fix the problem I installed voodoo =)

Yeah, Quicktime has a tendency to have those evil CPUIDs in it, possibly causing the problem described. I actually had an unpatched Quicktime install hose OS X back before Voodoo had an opcode patcher added in.
Get the Voodoo kernel as oneshot suggests and you should be better off.

Try this.

Maybe it's a hardware problem. I had a long time a Radeon X1600Pro, everything was working fine except QT 7.5 or higher. I now exchanged all my gfx cards to an Radeon HD2600XT and everything works fine. This thing supports resolutions up to 2048x1536 and full Dual-Monitor including TV. Great card.

I installed voodoo when I installed iPC. I was running quicktime 7.6 with Leo4all and the netkas kernel with no issues.
I have a gigabyte ga-965p-s3 with a pentium 4, geforce 8600gt. I am using different video drivers though

Okay.. figured it out.
When I did the install, I only used the latest MacBook Pro video driver package. Afterward I did the leopard graphics update 1.0 and EFI Studio strings. Before I used NVinject, NVkush and the EFI Studio strings. Don't know if all that is necessary but I did it again and everything works great