Earlier today I described a problem that is known to MS and has no solution yet.
In short - you can install (mean really install a working version) Hyper-V under Windows Server 2008, only if you set all locale settings to EN-US / USA Location. Every other attempt will lead to a broken installation.
I also promised that after this installation I will revert back to desired location settings to check if everything is going on well.
And the answer is ....
After installing the Hyper-V Role under EN-US Locale / USA Location forced to all system accounts also, you can safely revert back to the desired locale settings and the Hyper-V will continue working.