UBB.threads PHP Forum Software Community Forums UBB.classic UBB.classic 6 Support Lastnumber.cgi corrupt error

We are are experiencing the problem again. It seems that we will have an EXTREME slowdown and then we get blank done pages on the forums and no one can login. Whether they are trying to login into Control Panel or the forums for posting. Please help! I am trying to login to the CP to turn on the accelerator, but I can't get there.

Thanks!