Need help with a hack

I'm currently messing around with a dll, just a simple thing I created to try couple of things. I use an ud injector and it injects fine, however I stumble upon these annoying exception errors once I try any of the hotkeys in game (Exception code: C0000005 in msvcrt.dll) to be exact.

Currently I'm using virtual protect & memcpy to mess with the addies but I've tried other approaches as well, nothing works. Altough I spent some time researching on Hackshield, it's hard to find any more info besides that it hooks writeprocessmemory/readprocmem etc. So my question is, do I have to use detours or some sort of hooks to bypass this problem? I'm new at both of them so in that case, I would appreciate if I perhaps could get some pointers how to start off with it.

The reason I really wonder is because I have based my source on a pub warrock hack, that is only 1 month old and it seems to work without detours or other bypasses.

Ah, and it's c++ if someone didn't catch it.