I had a very similar problem which surfaced for the first time on Wednesday 6/24. This was the first time this had ever happened despite using the photo album feature many times. I spent more than an hour on 6/25 and here are the results.
What didn't work:
1) rebooting laptop; 2) closing WLM and rebooting; 3) disconnecting from internet (was unable to "work offline"); 4) deleting from Outbox (not only was there nothing in the outbox to delete, there wasn't even an outbox!); 5) trying to stop the loading from
the stalled window; 6) going into Control Panel and using the fix problem feature under WLM uninstall; and 7) rebooting modem.
What worked:
I couldn't find a solution online either but combined some recommendations I found with some of my own shots in the dark. Here's what I did somewhat at the same time: 1) searched my C drive for all files with an .eml extension. I then deleted the one
(there were actually two) with the name of the email containing the suspect photo; 2) installed WLM 2012 (I had been running 2011); 3) Deleted the suspect photo from my hard drive; and 4) rebooted the computer.
When it rebooted, the stuck window was gone and my queued up emails were dumped into my inbox. Since then it has been working fine.
Good luck!