not much to go on, if you could post your specs, you know, what pc youve got hardware, what plugs your using etc etc. also what settings your using for those plugs. With a little more info, mabye we can make some suggestions:
did it work when you were using the regular cd, only reason i ask is ive never heard of the game, but i know there are some funky copy protections out there, if it did work before you made an image of it, try using Deamon Tools to mount the iso as a regular cd drive and try that. If not than no help from this corner (yet).
I looked at the compatability list and it said the game worked perfectly with Lewpy's Glide plug. There weren't any entries about Pete's plugs though.
I also looked at a patch site(can't give a link) and didn't find any patch for MegamanX4, but I did see patches for MMX3 and MMX5. Sorry that didn't help much.
Have you tried using software plug-ins? Megaman X4 is a 2D game, using a 3D plug-in will have no affect on it whatsoever (well, maybe some filtering). Software plug-ins are much better for 2D gaming. I have a burnt copy of Megaman X4 and it works perfectly in VGS, movies and all.
I *think* EpsxE has a problem with MMX4 and MMX5 movies.
I only have MMX5 and for sure it does not display the 2 intro movies. Also I've read on a compatbility list that MMX4 works fine but no movies...
While in MMX5 this isn't too bad, it's pretty much annoying in MMX4 because there's a lot of movies explaining the story, 1 common for X and Zero, 5 for Zero, and 3 for X IIRC (can't you tell I love this game??).
HOWEVER, if the version you have is US you might consider yourself lucky because the US voice acting is HORRIBLE!!! I have the jap game (on Saturn ), and some month ago I stumbled upon the PC US version, and I hear BAD acting...Plus, you don't get boss prefight speach, i must bear ingame voice acting ("it's not over yet!"...yuck...), and intro/ending songs are removed...