Help - X3 Word2007 Vista64 Invalid class string

Hi, Im new to this forum so sorry if this has been covered elsewhere.

I have just installed Endnote X3 on a new machine,it worked well for one day,then the invalid class string error appeared.  I have tried running X3 first, then word; running word first, then X3; reinstalling (twice), reinstalling word (once).  I have seen some references to 'right click and run as an administrator, but cant find this option.  I have updated X3, and Word.  Can anyone suggest any fix please - thanks…Dave