Anyone finding Fast User Switching crashes Lion with Screensaver?

Yes, I have the same problem. Trying to switch users under Lion almost always crashes the system. Pity. Except for this, I was starting to like Lion.

+1 switching users under Lion is causing us either locked up grey screens or kernel panics.

Same thing happening for me with 2009 Mac Mini. I have had power cycle the maching with the power button several times. Screen goes grey and does not recover.

This is regularly happening to me. iMac (Late 2009) 21.5" with two user accounts.

+1 for me on our home iMac 27 - 2010 May/June with 5 user accounts, 3 of which are used regularly. It doesn't happen every time, but more often than not. If users log out, rather than attempt to switch logins, or switch to the login screen, it seems a little bit more stable.

My work MBP15 only has one account that is used, so can't tell if it would be happening on this.

I'm having the same issue on my MacBookPro6,1 when using the 'lock' command under alfredapp (activates login screen). Seems to be a lion bug and not an alfred issue.

This has stopped happening to me since turning off FileVault.

Still happening here each and every time we try to switch user accounts. No FileVault here at all.

I'm having the issue when trying to fast switch to another user. The annoying thing is that the password dialog beachballs, and you can't press the "cancel" X button. However, I've found that keyboard input still goes through, so if you know Ctl+F2 selects the Apple menu, you can cursor down to logout, which usually works and cancels the user switch. If it hangs at the login screen, then I don't know what to do there. You can also switch to another space and then be able to click on things again.

Not sure what's causing it, but I'm going to start noting when it happens whether or not Time Machine is spinning as well as if my daughter's account is logged in with Flash having run away in Safari because I can't think of anything else going on.

I'm finding the same problem (almost always if I try to login a new user when one is logged in, or switch to an existing logged in user).

It seems to be related somehow to SecurityAgent - if I login via ssh and kill the security agent process things get "unstuck".

I am also getting lockup. I can avoid by selecting 'Login window...' from drop down, then selecting user from there instead of from menu dropdown.

Mac OS X Lion 10.7.1 (11B26)

Been happening to me every day since Lion has been released...driving me crazy!

I know. Why won't Apple fix this???

Same here (on MacMini):

I had the same issue on my old Mini with 10.6 (it was 4 years old so I ignored it). But my brand new MacMini (Oct 2011) with 10.7.1 does it too.

I have power-save set to never, and disabled the screen saver. Then I log into two accounts, as soon as one logs off the beachball is there. It hangs.

I found a workaround - press the power button and put it to sleep; press space bar and it wakes up allright (I was doing the same on 10.6).

I think the issue is related to the screen saver, because when I logoff - and the sign-in screen appears after some time the screen save will kick in. BUT I HAVE DISABLED the bloody screen saver - because I want all CPU for my application; but it still draws the mathematical clouds (and slows down my background task). Also from the screen saver, there is no way to login back normally. Strange thing, the apps continues to work in the background; encoding MP4 or synching with the AppleTV (1st gen). Only to see the screen is not possible.

Another way is to enable SSH (remote login) and restart remotely via command line. Because powering off a running OS is NOT a good solution!