Try this, if it works...
1. In VS go to "Tools->Import and Export Settings..."
2. Select "Reset all settings"
3. Choose to save your settings first or just overwrite them
4. Choose the best settings for you. I chose "Visual C# Development Settings"
See if that helps. On some machines here at my work, people got the wrong settings and some menu items weren't showing up (Debug->Exceptions for example) and other VS behavior was different.
If that doesn't work, here are a few other questions:
1. Do you have a menu for "Build->Configuration Manager"? Does it have a drop-down for Debug, Release, etc?
2. Can you get to Project Properties, the Build tab? If so, does it have a "Configuration" drop-down for Debug, Release, etc?
You can also try this:
1. Right click on your toolbar, in a blank space and select "Customize...".
2. On the "Commands" tab, select Build on the left and "Solution Configurations" on the right. Drag "Solution Configurations" up to the toolbar.
This should give you the Debug, Release dropdown.
-ner