Almost always, when I launch Codeblocks and then go and do something else until it is fully loaded, I find that Codeblocks will not show up in the taskbar when it is done loading. When I shift-tab to it, it comes to the foreground and only then does it appear in the taskbar.
I always thought it might be my XP being a bit messed up after having been used extensively, but I reinstalled last week and the behaviour has not changed.