Usually certain features cause client errors, what feature are you using?
Some things to go over:
OHK - Causes errors in TD, MM, HM, and sometimes ZM. For ZM it depends on the hack you are using. Some hacks with OHK work in ZM, while other ones don't.
No Recoil - Seems like something you won't really see getting a client error, but I have tested it myself, if you abuse no reload(for example cornering a mutant and shooting @ it's head so it dies quicker) - then you'll get client errors.
No Reload - If you spam the fire button and the reload button, you might get a client error.
Those are a few common hack features that'll get you client errors with. Tell me the features/list the features so everyone can see where you might be getting client errors and which ones aren't causing it.