I have PGP 9.0.2 installed on my laptop. For some reason, PGPTray gets busy now and then and spikes the CPU load to 100%. No idea why, or what it's doing. Not a lot of disk activity, but it sure kicks the laptop's fan into high gear. Does this for 5-10 minutes or so, stops, then starts back up again maybe 15 minutes later.
After a little bit of digging, I found this thread in the PGP Forums that seemed to explain everything (something about PGPTray polling disks). But then toward the end of the thread it's mentioned that the problem was fixed with 9.0.2. So maybe I'm having another problem. I'll have to check and see if it's doing the same thing on the computer at home.