What the title says. All options in the "Build" tab are grayed out, and run and debug are grayed out in the "Run" tab. I can fix it by giving mono root, but I'm not too keen on having that as a permanent solution.
I have tried creating a new "Hello world" solution just for testing, tried different project file formats(vs 20xx, mono 1.0), reinstalling mono, installing/uninstalling monodevelop-debugger-gdb...
I've been able to run programs before, no idea what happened.
Using linux mint 12 and monodevelop 2.6
Any other info you might need?
I suggest you upgrade to the latest Monodevelop version (3.04). In past releases there was a little bug that allowed what you describe to happen. In my experience it was project specific, meaning, when happened, happened only in one project, usually the last one I was working on.
In the meantime here is a simple workaround to use when that problem happens: When that happened to me in the past (using version Monodevelop 2.6 on Ubuntu) I found that if I open, compile and run successfully another project, and then go back to try and compile the problematic project (in which the 'Build' options were greyed out) - the problem is solved and all 'Build' menu options become be available again.
I don't know what the bug was, but as I mentioned above, I did not experience the same bug in Monodevelop 3.04, so I recommend you upgrade.
Hope that helps!