I have a strange problem which seems to have recently appeared. I used to be able to press the keyboard shortcut CTRL + M + O to 'collapse to definitions' in VS2010 when editing code, but it seems suddenly the CTRL + M key seems to have stopped working. When I now press the key combination I get the Open File dialogue.
I have tried the obvious things like resetting the keyboard scheme in Tools > Options but this has had no effect, I did also check that the default mapping for the keys were present and no other settings were overriding it in VS2010.
I have tried searching for an answer on the internet but can't find any other solutions. Has anyone heard of this happening before and do you know of a way to resolve this problem.
In addition, I very recently installed the new Windows Live Essentials 2011 suite, I am starting to wonder if this has any relation to this, although I'm not sure why it would! I have not had any of the apps running whilst VS2010 has been open. This could be of course a red herring!
Start killing processes with Taskmgr.exe, Processes tab. You'll eventually find the one that's sucking Ctrl + M with a windows hook.
Just to confirm, from more than one question and comment about this, it is the Microsoft Bing toolbar that causes the problem. Uninstalling it is the only known workaround right now.
Skype was the culprit for me. Turns out I enabled keyboard shortcuts for it and Ctrl + M was "Mute Microphone". Hope this helps others.
I have Skype installed. It had CTRL + M enabled for muting microphone.
Check all open programs and check their settings/options/preferences to see if they are using system wide shortcut keys and disable/modify accordingly.
I'm running VS2010 inside VMWare Fusion on a Mac.
For me, it stopped working after updating VMWare Fusion to version 4.1.2
I fixed it by unticking "Minimize Window (⌘ - M)" in Preferences > Keyboard & Mouse > Fusion Shortcuts.
I had the same problem. Bing Bar was installed but disabled in both FF and IE (FF had disabled it itself on security grounds, in IE I disabled it). I couldn't find any process specifically for the Bing Bar, but Ctrl + M stopped working if IE was running. Unistalled the Bing Bar and the problem went away. Thanks:)
Also, just to confirm it's not a Visual Studio issue - Ctrl + M stopped working in other programs too (at least SQL Navigator, which is quite an old program that I doubt is aware of and trying to use the Bing Bar - my guess is that it takes over Ctrl + M from everything).
Reboot worked for me.
I experienced this same issue out of nowhere (CTRL+M stopped responding).
I read the suggestions here but I could not find what process was causing it. I rebooted my laptop & the problem was solved!
The culprit for me was an AutoHotKey script that had Ctrl+M bound but not doing anything. The solution was to remove the un-used binding from the script and re-load the script. After that, everything is working.
来源：https://stackoverflow.com/questions/3872144/vs2010-ctrlm-keyboard-shortcut-has-stopped-working