Windows 7: Editing an EXE with PE Explorer gives 0xc000005

Hello guys, Im currently in a bind and no idea where to go.

A friend of mine is an official reseller of some BGA work tools. One of the companies gives software to use along side there workstations. He has been given the go ahead to modify the exe to rebrand. As alot of the info is in chinese or poorly translated.

They have specifically said using PE Explorer should be fine to edit the parts needed. Like Header and the bad translations.

When me or him edit any of the information. When we save the new exe and load it it gives a 0xc000005 error. No matter what time of change is made. Any ideas. To clarify this is perfectly legal.