Hi.  Somebody please correct me if I'm wrong...but I believe that the Events module that came with DNN 4.0.2 was the original Events module.  Sometime in early 2006 (after DNN 4.0.2), Alan Vance took over the Events module project and gave it a major overhaul.  He graciously donated his AVCalendar module to the DNN project and made it the new Events module.  Therefore, the Events module in DNN versions 4.0.2 and 4.3.7 are very different animals.  This may be the source of your issue.

Again, I want to stress that I'm just taking a stab.  Anybody who knows differently should please speak up.

Continuing with my previous assumptions, did you have an extensive amount of data in the DNN 4.0.2 Events module that you wish to save?  If so, you'll want to dig around in the forum for information about migrating the data from the old Events module to the new Events module.  I know that there was a data migration path from the AVCalendar module to the new Events module, but I'm not sure if one existed from the original Events module.  If anyone else knows, please chime in at any time.

It's been my experience that funny things can sometimes happen during the DNN upgrade process.  Things don't always work the way you might expect.  For that matter, I don't think that things always work the way that the programmer expects, either!  If worse comes to worse (and you don't care about saving previous data), you can try uninstalling the Events module altogether, and then downloading and installing the latest version of the Events module.  This might clear things up a bit.  As always, make sure to backup your DNN Server before making any of these changes.

See Ya!
Van