Help Me - CRC Check and FileSize Check

The problem with dll must rely (almost for sure) in a module which calls Yours dll (it could be main executable) - that's the way I would do a check like this. Method for finding check in this case You should chose by Yourself. I suggest You set a breakpoint on ExitProcess or, if it hangs, back-trace to the place where the last (or "few" last) function are called and find the cause. Also, You can always notice correct order of function calling with untouched dll, then change Your dll and notice what's changing.