Problem with Transport counter jitters

[DrC:drive]

I am having a problem with the transport counter display, it is not rolling smoothly but seems to pause for a moment every few beats as does the scroll cursor, and then restart as if its stalling temporarily. It is cured by reinstalling PT but then recurs again spontaneously. Its quite annoying since the scrolling cursor pauses as well and its difficult to see where you are in the track.
Mac G4 350mhz, 704 MB RAM, os 9.04, PT 5.1.1, Control 24

Anysuggestions how this might be fixed

Cheers

James Cullen
Nimrod Audio

[Jan Folkson]

Having a Direct-Connect plug in enabled without it's corresponding application opened will cause this.

[letrev]

This can also be caused by a CPU drain or inadequate memory buffer settings. If you have a ton of RTAS plugs running, try taking a few out or switch them to TDM.