Start>> Settings>> Control Panel>> Administrative Tools>> Event Viewer
Once the Event Viewer is open highlight each of the three entries in the left column in turn and see if there are an errors listed relating to Fireworks. If there are any they will probably be in the Application section. Double click on the error in the right hand panel to get further details and often there is a link to more help on the web.
The point about it is though, that it may well offer you more information to go on than the error message alone, which is not one I've seen before.
Two things to try:
1. if you have any Fireworks extensions installed try disabling them through the extension manager and see if that improves things.
2. Tweak UI in Windows XP can cause an internal error message in Fireworks according to Macromedia support.