I've spent the last few days troubleshooting a hang problem where data file open hangs part way through the open process. The window opens, the menus populate, and the account list populates, but then the process hangs and focus is never returned to the user.
Skipping past all the myriad things I tried that did not resolve the problem … the issue turned out to be that my storage location for Automatic Local Backups had stopped responding. The real problem had nothing to do with Quicken, but showed up as a Quicken hang during open.
Apparently Quicken validates the local backup location during file open and gets stuck when it doesn't respond. A GREAT PRODUCT IMPROVEMENT would be for that validation to time out and an error message to surface reporting the missing backup location.
This is a lesson I had learned before, forgot, and had the pleasure of re-learning, so I thought I'd share it here in case others have had a similar problem and might benefit.