Also I've a bug even on newer nightlies, sometimes I open a project in codeblocks and the "Build" icon (the gear) remains greyed, i.e. I can't click on it. When that happens I close codeblocks and reopen codeblocks + the project until it works (usually straightaway).
I dunno how to reproduce it but the icon is not greyed because there is a background compilation or because the built process is running, this happens even just after a reboot.