-Download/run latest version of hijackthis.
-Go to DaniWeb IT Community > Tech Talk > Microsoft Windows > Viruses, Spyware & other Nasties to post your log for evaluation, or go here: http://www.hijackthis.de/ to analyze it yourself.
Other than that, you'll need to be more specific on a few things.
Exactly what programs/applications were running at the time of the error? Please write them down and find the common denominator. If you experience this error without any apps running (like being away from your computer for a while with nothing in the taskbar) it's most certainly a background process, which is probably adware/spyware/malware.
Otherwise, after cleaning via hijackthis, if you still experience this error, you're going to have to play process of elimination with your running processes.