When I open Mail for the 1irst time after installing Lion, I get the dialog box popup that says that my messages need to be upgraded the first time I use mail. "Click Continue to upgrade your messages now, or click Quit to upgrade later." I click continue, and the box changes, indicating the messages are being upgraded, but it immediately quits. The upgrade boz is not even up for a half second. Trying to launch mail again brings me back to square one, and the same thing happens again. I practice inbox zero and all of my accounts are IMAP, so I can't imagine it's choking on my inbox load. Has anyone experienced the same problem? Any ideas for solutions? I tried searching to no avail. Thank you.