Visual Studio 2010 doesn't rebuild changed code unless I manually select "Rebuild"

Gah, I figured this out. It was naturally something stupid I did when messing around with build settings after a too-late night. Here are the things to check:

1. Tools >> Options >> Project and Solution >> Build and Run >> Check that "On run, when projects are out of date" is set to "Always build" or "Prompt to build"
2. Build >> Configuration Manager >> Check that "Build" is checked for all of the projects you want to build for each of the configurations you need to use.

Also if multiple projects in solution, check configuration manager. If you have some projects "Any CPU" and some "x86", will be builded only projects of same arhitecture. Same with "Debug" and "Realese" config.