OMC central services DLL or Internal Error ?

[Perceval]

Hello all !
I'd like to configure mail notification on voicemail, which belongs to Central Services.
When I try to access the central services from OMC (the latest 51.0.1.01 in Expert mode, one of the last items, global information), I get "Unable to open the DLL."
I've set up OMC on a fresh Windows 7, and I got ERROR - InternalCentralServiceError".
The button is greyed when trying from the phones detail list too.

Any idea ? I feel a bit stuck on this. Thanks a lot !!

[Perceval]

News : I've updated my main computer from R51.0_8.1a to R51.0_10.1a (the latest one) and now it works. I just don't know at all why. And it doesn't solve the fact that I have this error on another different computer I've reset yesterday (completely different hardware and software).
Let's say this is solved, I've setup my mail, so now I'll have to see how it works.

I'll investigate this problem later... I'll check the DLL, because all the services stand on one dll.