GPF errors can happen for all sorts of reasons. The next time you receive a GPF error, if prompted, paste the GPF error report details by pressing CTL+V into an email. Be sure to include the steps you took up until the point where the GPF error happened. That will help us troubleshoot this issue more effectively.
Also, if you've experienced received a GPF after using GoToMeeting or GoToWebinar, in most cases rebooting your machine seems to resolve the GPF error issue.
