change in VB EXE file.

[Michel]

I force the JNE jumps to PUSH 0000CC81 ("Professional Version" for About dialogbox). But, if the previous TEST EAX, EAX is Zero, next JMP to PUSH 0000CC82 ("Trial Version").

Are you sure the real test is not before this "test eax", and that the "jne" is not only the way to show the right message in the about-box ? If this is the case, another part of the prog may perform the test too and produce some incompatibility.
So, the first thing would be to be sure you have found the very ROOT of the Prof-Trial test, and patch that, not the message.
Other thing : you may try to leave the JNE and exchange the two PUCHs : no more crc-check problem, and see what happen...
Good luck.