Alt+f4 doesn't work for me either. Quickbooks just forced this update on me last night, and I got the popup to log in to an account for the first time. Today I found this thread and tried Alt+f4 but nothing happens. The only way I've found to close that popup is to use the task manager to close QB entirely. Now there's no way for me to access my own company file on my own PC without logging in to Intuit, opening a security hole, and giving Intuit access to all my data. Intuit, you need to fix this mistake now.