Depending on what version you're currently using, the next version might fix it.

Certainly, DOSBOX 0.72. 😉

Gamemode -- full screen.

The original Doom II v1.9 does not cause any DosBox hangs here when alt-tabbing. I have alt-tabbed at least 5 times during the menu and during game-playing on each run. No crashes at all. Alt-entered 3 times. Finally, I just pressed f10, y and typed exit. No problems whatsoever.

Successfully tested on:

Microsoft (R) Windows (R) Vista(TM) Ultimate 32-bit Edition
Service Pack 1 + All the latest updates have been installed.

DosBox release:
Official stable DosBox 0.72 from <http://www.dosbox.com/>.

Three stability loops have been executed. I did experience one minor issue that seemed like a crash on one of the runs, but it is not a crash per se. Instead, it's a problem in dosbox that causes the screen to remain unrefreshed which at first glance appears as a frozen screen. Obviously that creates a false impression of a dosbox hang, but all you need to do is force a dosbox screen update and you'll see a moving picture again.

Still there might be a problem with slow fullscreen switches that can cause
the game to crash, next version should fix that.

Sure, but I could not possibly reproduce that full-screen/alt-tab/alt-enter completely irrecoverable hang/crash under stringent testing procedures. And that's not the first time I play Doom II v1.9 on DosBox 0.72 on my Vista (TM) Ultimate.

My original Doom II has witnessed at least three iterations of DosBox and two iterations of Windows-es. No crashes at all, either on the Concurrent Versioning System build or the stable edition.

OK, I've tried to reproduce the problem again. Hanging is reproduced only in case when alt-tabbing from full-screen mode.

Thank you.

Hmm, can you please provide your full system specifications?

In addition to your operating system, can you provide your running processes list in Task Manager, the size of the Operating Memory (RAM) installed in your computer, your video card, the version of your video card drivers, your sound card and its driver version, the motherboard, CPU, et cetera. Furthermore, providing any additional devices that you are using would be useful.

Also, it is a good idea to update your operating system to Service Pack 3, and install all remaining Microsoft updates after SP3 has been completely installed. Is there any particular reason that prevents you from installing SP3? Probably backwards compatibility?

And, as usual, make sure you have updated your motherboard chipset drivers, your video card drivers, and your sound card drivers.

It is a good idea to update your DirectX 9 as well. Here is a good place to do that.

Good luck.

As i've noted above it is KNOWN to happen when there are some delays
and cycles=max (or =auto for pmode games as in this case) which might
be caused by fullscreen switching. You will NOT be able to reproduce this
if the delays don't happen on your system.