Well, There seems to be many possibilities to this problem, as most of you have already received replies.
My problem was still a little different though.
It seems that my colleague started having problems with his email system when the Pro.e problem arose. Just as mine did. Once our support group fixed my email problem yesterday (installing Service Pack 3 for MS Office), my pro.e stopped crashing as well, when using the assembly window.
This was definately a Windows issue, and not necessarily a Pro.E issue.
Thanks to everyone who replied.
This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.