Glad to see I'm not the only one to have this issue. PTC cannot replicate and has closed the case for now. They gave us some more logging to enable but we haven't had a chance to try it yet
Please enable the user-mode local dump to generate full crash dump whenever explorer crashes and send the dump for analysis. Please refer below articles to configure the local dump. Basically you just need to add few registry entries.
http://msdn.microsoft.com/en-us/library/windows/desktop/bb787181%28v=vs.85%29.aspx