I'm using MAME32 ver .91, and it's displaying all my vertical shmups in tate no matter what I do, and I can't turn this monitor on it's side. I tried deleting all the ini. files and it still does it. I remember this happened once before, but I don't remember what I did to fix it. I would use the newest MAME, but for some reason, it only wants to play half of the games I have. Thanks in advance.
Tried banging on the number pad's 0/Ins key? I don't remember if .91 is new enough to use the new video system, but it's worth a try...should also be a GUI option to rotate it as well.
This happened to me recently when I installed MAME to another machine. What you need to do is go to "Options --> Default game options," then click on the "Advanced" tab, then uncheck "Stretch using hardware."
When this happened to me on one computer I had to play the games windowed to get them to work properly. It's not anything near an ideal solution, but it'll get them running at the right ratio and orientation.