I've already asked about this, but the replies didn't help, and I've worked out a bit more about the problem.
Every time I edit cp.cgi i cannot access the Control Panel (Internal Server Error), and every time I edit ultimatebb.cgi I cannot access the UBB (internal server error).
It is not the permissions, and every time I tried the hacks, I followed the instructions exactly. Those are the only pages affected. I am using v6.1.0.3.