Sup suzie. I have an ATI 4670 and have had no end of problems with the graphics drivers - the older card makes are really really buggy. Certain games have a tendency to crash my system entirely - it's a real pain in the arse.
What I will suggest, and its the only solution that has ever worked for me is to download driver sweeper from
here (download is about half down the page). Uninstall through add/remove programs. Run your system in safe mode (restart and keep hitting F8 until the boot menu shows up). Run driver sweeper and remove all trace of the ATI drivers you have and then reinstall the driver that came with the system - hopefully you have the original disk.
For future reference ATI always recommend either completely uninstalling old drivers before applying new ones or not to update it all unless completely necessary.
Here is another forum post regarding the 3550 and they suggest the same thing.
However, some people say that a system roll-back will do the trick. If you're not happy about doing any of this then maybe raise the question on the AMD boards as they should know a lot more specific information about it than myself.
BACK-UP. Whenever dealing with something like this you should always backup your valuable stuff. And I cannot guarantee this will work, and if you're not happy troubleshooting problems which might arise from doing this then let a professional take a look.