What is ATSServer, and why is it freezing my Mac?

Whenever I open Microsoft PowerPoint 2008 on my MacBook Pro, I get more beach balls than a summer vacation to Florida! I try to click anywhere or manipulate something and it will take about 30 seconds before it will respond. Even if I click out of the program, the system is still clunky.

I checked the Activity Monitor and see that a process called "ATSServer" is taking up 25-50% of my processor activity. I read this is something to do with fonts. I cleared by Font Cache and restarted, but it didn't do anything.

I've got 10.5.2 on a 2.4 Ghz MacBook Pro, 4 GB Ram. Office 2008 has all updates.

Thanks so much for your help!

An update: I've found this also happens with opening some Excel files. The same ATSServer goes out of control.

I guess this is stumping everyone else as well...