Maybe that particular mod didn't touch the buttons?
Out of curiosity, have you restarted your PC since installing this theme?
Hmm, I remember having issues like this when I tried to install my theme but I don't remember how I got it working.Did the installation instructions mention anything about needing to patch your system?
if you forget up, force shut down and when windows is starting force shutdown again, the second time it starts you will have an option to go into repair mode and hopefully that can fix anything you might have messed up