RE:
Isn't there a problem with administrator rights with the new versions of windows?
Make sure you're running UTAU with full administrator powers.
As side note, I've seen UTAU resampler.exe not working because the cmd (the black window thing) was blocked by the administrator. (Not your case as you can run resampler.exe)
Another posible issue could be a path name with weird characters (like, C:\Prögramç Filesñ한국\UTAU\). But... you know, not the case, isn't it?
Some resamplers don't work for some voicebanks for various reasons (samples in stereo, working with other than 44100Hz, low frequency noise, leprechauns, etc). But if the voicebank worked with those resamplers in your old windows then I doubt it's your case so you shouldn't worry about these issues.