That error is generated by the rundll32.exe system file, which is responsible for managing numerous other components. To give us a better idea of which exact program/module rundll32 is having trouble with, please click on the "More info" button in the error message dialog box and post the full and exact text of what you see there.

Alternately, you can look at your system and application logs to see if they contain additional information on the error. To view the logs, open the Event Viewer utility in your Administrative Tools control panel.