I'm on a Win7, 64bit, with CS6 (13.0 (13.0 20120315.r.428 2012/03/15:21:00:00). The keyboard shortcut to bring up the Canvas resize menu is ctl+alt+c. That combination does nothing. If I add the Windows key to the combo, then it will bring up the Canvas resize menu. Could others check to see if it works for them or have I found another bug?
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.