Odd, I've never once seen a message like that, and it strikes me that it might possibly be some kind of malware.
In any event, Catalyst is ATI/AMD's name for their video drivers, so all you need to do is go to the AMD website, download the latest set of drivers for whatever video card you have in your system (at 7 years old, it will likely be the legacy set of drivers), install them, and then if the error keeps appearing I would suspect that either A) it's malware related, or B) your OS install is corrupt.
For that matter, it might not hurt to make sure your system even has some kind of ATI video card/chip in it, it might just have an Intel video chip, in which case my malware suspicion would seem considerably more likely.
After booting up, I get the message "ATI Catalyst is missing a driver." I ignored it the first time (yesterday) but when I saw it again, I clicked on the link to a Microsoft error-reporting page, which told me to downlad and install the driver for ATI catalyst. I had no idea what that was, and the link to ATI just brought me to a home page, not the promised instructions to download. I gather from some research that this concerns video, which I haven't had any problems with. I have been having sound problems, but they pre-date this error message. Also, searching these forums leads me to think downloading the driver (even if I could figure out how to) might not be the best idea. Can anyone clue me in, in lay-friendly language? I have an almost 7-yr-old Dell Dimension 9100 desktop running XP (SP3). I allow Windows updates when notified that they're available.