Has Visual Studio 2005 stopped responding to arrow keys, do shortcut keys not work anymore? Only alphanumeric keys work? This is caused by a bug in the keybindings code, but fortunately there is an easy workaround. From a command prompt, run devenv /resetuserdata. This will cause all of your user settings to be reset, but you can work around that easily enough by exporting all of your settings other than those related to keybindings before resetting, then importing all of those settings after you start up the IDE again.
The root cause bug is fixed in VS 2005 SP1 (including the Beta).