On Debian Wheezy 64bit with Cinnamon desktop on Intel graphics I have a similar problem.
With SPAZ, somebody sent me a message causing a steam popup. This caused the game to be pulled out of fullscreen mode and into windowed. For SPAZ this locked up the game. When I got it back into fullscreen mode I could not do anything and was forced to SSH into my computer from my tablet to kill the process.
With Dungeons of Dredmor, earning achievements causes the game to exit fullscreen mode and I can not get it back into fullscreen. With this one I tried with Steam in-game enabled and disabled and got the same results.
I suspect Steam is displaying a desktop notification when it should not be because a game is in fullscreen. Maybe because the in-game overlay is not working properly so it doesn't know a game is in fullscreen?
I have almost the same setup and problem as @epitron. Arch Linux XFCE4 with latest Catalyst drivers. As soon as I get an achievement in TF2, the notification steals focus. After getting back to the game, the game is unplayable choppy in both audio and video and I have to kill the application.
Do you have a CrashID?
On Ubuntu 12.10 with Nvidia Optimus (via Bumblebee) it doesn't crash, but the game minimizes and I have to click the icon again to get back to fullscreen. That's pretty annoying.
I have 12.10 64bit and I got the same problem the achievement box steal the focus from TF2, most of the time I can't get back to the game normally because all I can see is a whitescreen
There are two bugs here, one being focus stealing by Steam notification toasts, the other being game crash as a result. We're looking at the focus stealing now and will have it fixed soon after New Years. For the game crash, we need the CrashID to see what's going on. In Steam->Help->System Information, if you scroll to the end, there will be CrashID(s) listed. Please post them here. Thanks.
I posted the crash dumps a few days ago, but the comment seems to have been deleted. (The title of this bug also changed. Someone be messin' wit me!)
Recent Failure Reports:
Wed Dec 19 21:49:53 2012 GMT: file ''/tmp/dumps/assert_20121219164949_1.dmp'', upload yes: ''CrashID=bp-85239267-20b6-489e-97f4-22b2f2121219''
Thu Dec 20 19:51:52 2012 GMT: file ''/tmp/dumps/assert_20121220145150_1.dmp'', upload yes: ''CrashID=bp-bc6be5c0-2011-4621-8b21-8e17a2121220''
Thu Dec 20 20:09:54 2012 GMT: file ''/tmp/dumps/crash_20121220150952_1.dmp'', upload yes: ''CrashID=bp-8f48c864-40d5-41aa-b730-c8db32121220''
Fri Dec 21 07:56:05 2012 GMT: file ''/tmp/dumps/assert_20121221025604_1.dmp'', upload yes: ''CrashID=bp-a7f68b9b-c237-4f53-9945-94aaa2121220''
Sat Dec 22 07:19:18 2012 GMT: file ''/tmp/dumps/assert_20121222021918_1.dmp'', upload no: ''HTTP response code said error''
Sat Dec 22 20:24:06 2012 GMT: file ''/tmp/dumps/assert_20121222152405_1.dmp'', upload yes: ''CrashID=bp-ac0912fa-10a1-4766-81eb-0f3702121222''
I played TF2 for a while today (it doesn't seem to be as jittery on certain maps), and the game didn't crash after the achievement stole focus, and I switched back. I switched back by clicking the achievement popup, however -- normally I click the window button on the taskbar.
the same
The focus stealing problem is now fixed and will be in the next update (after New Years).
Thank you for the crash ids. We'll be looking at these next.
And i have the same problem on Arch Linux with KDE (game is minimalizing after getting achievement)
I've got another crash dump, if you need it: http://chris.ill-logic.com/files/crash_20121224223619_1.dmp
(The dump didn't upload for some reason.. I got this: Tue Dec 25 03:36:19 2012 GMT: file ''/tmp/dumps/crash_20121224223619_1.dmp'', upload no: ''HTTP response code said error'')
It doesn't crash my gameplay (before), but it gets away the focus of the game. You are switched back to your desktop.
Nothing extracted yet.
I'm running Steam & Team Fortress 2 on Arch Linux under XFCE4 with the latest NVidia drivers.
When I get an achievement, steam's little popup steals focus from the TF2 window, switching me back to the desktop. Then, when I click to go back to the TF2 window, TF2 instantly crashes.
(I have the in-game Steam disabled, by the way. Could that be the culprit?)