I didn't make it!
Okay, i randomly get this error when playing JA MP and it disconnects me: When it does happen, it happens alot meaning its not a "one time thing" Error: RB_EndSurface()-SHADER_MAX_INDEXES_hit
You probably have too many files with shader files in them. Shader files can be found in map, skin, vehicle, and other .pk3 files you have downloaded. Remove any .pk3 files that you aren't really using or need from your base folder.
Yep, I have experienced this of sorts, but only in JKO (so far).
This is only an occasional error in mp for me. I would have thought that the way the JKO/JKA engines work, loading all the skin files that u have in the base so they are available for u to change to in game, that it would be a more common occurence. What happens in JKO is that u get an error message like yours which say basically, max number of shaders . After this, the player/ model/skins in game that u change to have no textures on them at all.
Bear in mind that the JKA/O communities exist in order to get more out of the games/gameplay than the developers ever planned or anticipated, so be prepared to hit the limits every now and again. The important thing is we understand why these things happen and can correct any ill effects they cause without trashing your machine and/or files.