Strange flashing along top of screen on Ultimate Doom

[kwikshot]

When I pick up items, sometimes the game will lock up for a short period of time and then for the remainder of the game the top black bar on the screen will be flashing yellow, the same happens if you get hit, the top black bar will flash red...

It must be a problem with the screen flashing, sometimes it just doesn't happen at all but it does most of the time...

I know I could just use a source port but I really like the Steam (DosBox) version!

[Nitronumber9]

It sounds like Dosbox's resolution isn't correct for your screen or some inconstancy along those lines.
You have two solutions which should work, and a 3rd which may work, these are.

Solution One
Within the steam directory for Doom theres a config file (should be called Doom.cfg or UltimateDoom.cfg, note there are two, one for mouse control, one without, choose the one you wish to edit) I can't remember the exact command to do it, but it should be in a block of three, one command changes the rendering method (try that as well, it may help) the other changes horizontal resolution and the last vertical resolution.

Solution Two
Download Chocolate Doom, ok its a sourceport, but it aims to stay as close to Doom as possible, I'll even say its closer than Dosbox is to the original Doom, it even displays your game in a lovely 4:3 format if your a nostalgia fan.

Solution Three
If you have Doom2 on steam, you can copy and rename the config for Doom2 for Ultimate Doom, I can't promise that will work, but I found the Doom2 cfg to be less glitchy than the ultimate doom config.

[Kouvero]

What finally did it for me was changing the following line in ultimatem.conf (or ultimate.conf if you don't use mouse while playing?):

output=surface TO output=ddraw