Can you run this against the database and see if that solves it:
Exec mp_ModuleSettings_SyncDefinitions
Is it possible that you are accessing the site from behind a caching proxy server? Maybe the blank page is cached somewhere. try refreshing the page a few times after running the procedure above.
If that fails to resolve it I really think the best thing to do is to upgrade to mojoPortal 2.3.6.7 and then re-deploy the latest version of Event Calendar Pro. If you backup the site and the database before hand then it would be possible to get back to the current state if something goes wrong with the upgrade so for safety it would be best to do that, but really I don't expect problems with the upgrade and if there are problems we will try to help.
Hope that helps,
Joe