The problem occurs whenever you hit clear the feed cache from the feed manager.
Not for me it doesn't, that is why I asked what feed urls you are using. It must be something bad in the feed that it isn't handling correctly. I need the bad feed url so I can produce the error and diagnose it.
The new sts-event calander crashes the site whenever installed.
please start a new thread about that problem and post the error detail. Re-installing, you possibly used the wrong versions of the dlls for Event Calendar Pro, it includes versions for 3.5 and 4.0 .NET and you must make sure to sue the correct ones.