So I download my old faves, Ultimate Doom, Final Doom, Doom II, etc. and find to my confusion that every time I click a menu item - options, begin game, anything except exit - the menu instantly clicks back one level as if I'd hit ESC or something.

I presume this is some bizarre keybind issue - though I'm not touching any keys. Any ideas?

FIXED - I un-set then reset the control scheme in the setup application. I don't know what was sicking but that unstuck it. Demons beware!

Thanks for posting your solution. I've been having the same issues and submitted a ticket about it.

Sounds like GOG have a bad setup config in the provided DOSBox version of the game, as not only has this issue happened to some, but so has missing music due to bad sound setup.

The game is much better when played using a source port, however, and by doing so both of these issues are avoided as you only need the WAD files from the games.

I don't know about the music issue as I have it turned down.
I think the issue with the menu might be caused by the mouse, I've found clicking and moving the mouse about switches control back to normal.

Youre right!
Thanks!