Nah, mods work good. When you make models bigger than they should be, then game reminds you via error message, and when you change them back it works just fine. Only anticheat measure is ironsight checksum. When you change semi.png, it gets new checksum. Game will let you join server, it'll even let you play with new ironsights, but your screen turns round and round like crazy and you don't see anything.

Maybe you video card isn't good.

Or have you edited any of the .kv6 files of the player parts? Then the game does weird things to prevent cheating.

Or perhaps you should reinstall Ace of Spades.

Whenever I try to play on a server that works, I get a black screen and have to close the game with Task Manager.