Crackling with Videotrack playing

Hi all.

I am working with an MP4 videotrack. The problem is when i view the video i get massive amounts of crackling that makes it impossible to write to the videotrack.

This is holding me back big time! Any ideas are gratefully received.

Thanks in advance,

Specs? Mac? PC? OS? Processer? Ram? Sound card? Buffer settings? Video card? How big is the project? Audio? VIs? Plugs? 64-bit? 32? Video codec?

In the Cubase 5.5 was changed video engine in Cubase. Now, it works on Quick Time. Check you CPU, RAM and HDD usage. And send us the specification, as Jeff wrote.