7.2 CPU overload clicks when recording

I've recently upgraded to 7.2, and I'm now getting sporadic clicks when I'm recording within Protools. It happens when I'm recording to a track via a bus and when doing a 'bounce to disk'. The CPU usage bar clips at maximum and there is a corresponding splat in the audio at that point. Sometimes there will be three or four in a row, sometimes the odd one, sometimes nothing for 10 minutes or more. The weird thing is that its occuring with projects that I did all the way back at 6.9 that I'm having to go back and update as well as new projects. I'm running 7.2cs1 on an HD2 2GHz G5 (PPC). It happens on all sorts of sessions, regardless of what plugins I'm running (I have the usual digi stuff and Waves Gold), what the track count is, or what the sampling rate or bit depth are. There are no applications running in the background (that I'm aware of). Has anyone else had this problem, or have any ideas that I might be able to do to fault find the problem and resolve it? Many thanks!! Matthew edit - I've read the other post about clicking in 7.2, but I'm not experiencing any of those problems and all plugs are up to date....

How did you verify that all plug-ins are up to date? Did you trash preferences after updating plug-ins?

When I installed 7.2 I downloaded all the latest versions of the digi plugins, and updated my Waves. I didn't trash the preferences, but I have done now, and it seems to have cleared the problem! I'm now feeling silly, as I should have thought of that - thanks! Mat