I play offline. I do have quite a lot of mods, but something is driving me insane. I play against bots, and I always come across this error. If I have more than ten bots in a game at the same time, it crashes back to the main menu with this error. I don't even play online. No matter what the map, it always does this. Even in duels where there is only myself and the bot this has happened! Can anyone explain why this is so?
What mods are you talking about? Skins/models? Maps? Custom weapons? Large mods (JaPlus, ClanMod, etc.)? In any case, try removing some of those mods to see if the problem disappears. I've never seen this error before, so I don't know what exactly is the problem. Perhaps you have too many player models/bots installed. I could be wrong, ofcourse.
Is that the full error or just apart of it? Coz it looks like there is a file in a mod with exceptionally long name or data to it.
It sounds to me like you have a bot with a lot of data. There is a limit on the amount of data bots can have on them. Try removing the bots that you don't spawn, and see if it helps.
Search the web for MAX_GAMESTATE_CHARS (I'm too lazy right now); that's the usual q3 term for it (and also to be found in q_shared.h, for that matter). Maybe you'll find something helpful.