I copied my Liberkey installation to backup drive. Then cleaned my HDD, reinstalling Windows XP, then after everything worked again, copied back Liberkey.
Only difference, it used to on my G: drive, now it sits on my D: drive.
I get the blue button, but when I press it nothing apparently happens.
Any advice where to look?

It's fixed. Some files had disappeared. I copied them from my mobile Liberkey and everything's working fine again.