I'm having the same issue.  I deleted the module definition, reuploaded from a fresh install, still the error persists.  I upgraded to 4.3.5 for DNN in addition to trying to get it working again. 

Ideas would be nice.

Aha!  That was precisely the problem.  I wonder what changed my connection string on me because it had previously been correct (or maybe I was just imagining things).  At any rate, I now understand what you meant in your previous post about it revealing the error in your connection string and then reinstalling 3.02 was ok.  For the DNN developers, this is something to look in to either for what is changing the connection string from whatever DB we chose to DotNetNuke (mine was DNNTest) or in the least, get the error reporting back in that 3.01 was using.  3.02 was merely reporting a module error, whereas 3.01 narrowed it down to the connection string -- seems to me just the placement of the try-catch is what is changing how the error is reported.

Thanks a million mvanzwieten for helping figure that one out.

No prob, Foob!  Glad its working again!  :)  Do you have any experience with changing the look/feel around of the calendar with the .css file, or do you just keep it plain-jane?  I'm trying to find out if there are any sites out there that offer modified calendar .css files so we can just copy & paste and use them, instead of figuring out all that stuff ourselves?  (Kinda like the skins).  Thanks!