H2K_Lord_Maul has reported there is a potential problem that can cause servers to crash after applying the 451 patch. H2K and the UTPG team determined that if you have packages that have been flagged as "ServerSide only", this will happen.
NOTE: if you have followed the technic described in the "Advanced Aimbot Protection" tutorial here, this will effect you
The solution is to re-flag the files after the patch is applied.