There's a problem with memory initialization, so test your port from a cold reset (turn off with the power switch).
just tested this. no dice. in fact, prboom starts and executes correctly every time, at any time, as long as you're running the shareware doom.
You'll also need the PrBoom.wad in addition to the WAD file you want to use.
i know about that. packed or unpacked, it makes no difference. both methods were tested and both work... as long as you're providing doom1.wad containing the shareware version of doom; renaming another iwad to doom1.wad fails, as expected
If you tell me exactly which IWAD you are trying to use I could check if the program is complaining about something though the debug port when I had some time (I'm very busy lately).
any standard iwad will do, doom, doom2, tnt evilution, plutonia, ultimate... in fact, if you're tipsy about testing these iwads, why not test it with freedoom? check the link above. both freedoom.wad and freedoomu.wad will fail, even the "demo" version (with its tiny size of six megs) will be rejected. (though gzdoom on my laptop also complains about that demo, but at least it shows the start screen before exploding)
no problem about waiting. take your time.