Endnote X4 crashes after saving changes to records (Mac)

I’ve recently upgraded to EdnnoteX4 so that I can use it with Office 2011 for Mac. It works fine uless I make a change to a record eg attaching a pdf. When I select save changes to record, the program crashes. Almost every time. This occurs whether or not Word is open. I cant see any mention of this on the boards. Is anyone else having this problem and any ideas how to fix it?