Hitting login then gives...

Code:
WebAppServer.WebBusinessProcess.19.0 error '80020009'

Application error occurred during processing.Technical details for the site administrator: Unhandled exception occurred while processing get_PreviousLessonURL. Please check the Windows event log for further information about the problem.

/lesson.asp, line 91
Tried reloading the page.. 1 time, 2 times (still same error) and... gave up.
19.0
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Wil