We are having the same issue.   I have always used the esc button to go back to previous screen and never used the X button, but now sometimes when we use it, it crashes QB and closes.   This happens many times a day, not just for me but my clerk.   Somedays it does it and somedays it doesn't.   I also get an error some nights that says QBWebConnector - Information - QBWC1085 : There was a problem with the log file QB Web Connector will continue without a log file.   Ever since I started getting this issue after we upgraded to enterprise is when the ESC button issue started.   My IT guy tried to do the fix for the webconnector area but it didn't help it still happens.   I think it has something to do with our Zedaxis we use, but again this never happened until we switched to enterprise.