I agree.
*CAUTION! TAMPERING WITH YOUR REGISTRY CAN SCREW UP YOUR OS*
However, as long as you're doubly careful about what you 'actually' edit, you should be alright.
To access the registry click Start -> Run -> Type in 'regedit', hit Return or click Open.
Now, look for HKEY_LOCAL_MACHINE.
This directory contains information about the hardware and software settings that are generic to all users of this particular computer.
You should be able to see a directory called SOFTWARE. Basically, because you don't know what the specific Ubisoft Registry Keys are you will just have to hunt around for them.
I would suggest trying to get the Registry Keys off Ubi. Chances are though they won't know, so in that event just have a look around. Remember though, once you delete a registry key - that IS IT.
Bon chance mon ami.
Post if you need more help
