I get the same issue, only I can't change the login settings because our company also accepts credit card payments, and we have the credit card protection enabled.  Any other ideas on how to fix this?

I can't remember when we started having this issue, but seems like it has been this way for a while.  We would just try not to have the file open and not be actively using the program while being open.  At times we have a customer or other employee come in to talk for a few minutes, and when we go back to the file, it is locked up and shows the lost connection to the file window with the abort button below.