Working here on windows 8 photoshop cs6.
Do you have any problems with other keyboard shortcuts in photoshop cs6?
For example does Alt+Ctrl+i bring up the Image Resize dialog?
I haven't had any other problems with keyboard shortcuts other than - http://forums.adobe.com/message/4435659#4435659.
Yes, ctl+alt+i brings up the resize. The funny thing is adding the Windows key (the one between ctl & alt) makes it work fine. Ctl+c will copy.
The obvious first step would be to go Edit > Keyboard shortcuts > Application Menus > Canvas size and see it is actually still set to Ctrl Alt c
I don't know if you can reset to defaults without deleting your Preferences file, but that would be a pretty safe bet to fix it.
It does show up that way. I just went into the Keyboard shortcuts and deleted that one and restarted Photoshop. I went back to the Keyboard shortcuts and it didn't show one for the Canvas Size. I tried to add Alt+Ctl+c and it would not accept it. It would add it if I used Alt+Ctl+Win+c. Alt+Ctl+v works as does Alt+Ctl+Z. I'll do some more checking.
*edit - I just checked ctl+alt+shf+c and it works as well.
I found the problem! It seems that keystroke combo was taken over by my video card software, AMD Catalyst Control Center. It was set up as a hotkey in the CCC preferences to launch the CCC. The funny thing is that the Enable Hotkeys Feature and the Active boxes were unchecked. When they were checked, pressing ctl+alt+c would indeed start up the CCC. I had to edit the Hotkey to blank and now it works as it should.
It also affected MS-Word as ctl+alt+c will give the copyright symbol.
Thanks for letting us know.
Those things can be a real bugger.
Thanks Dan, I changed PCs recently and couldn't understand why this short cut had stopped working. Turns out I had AMD Catalyst Control Center taking over that option too.