known bug : Opened Files Window has title "Disassembly"
If it's the first time you install Code::Blocks, that shouldn't happen.
Quick fix for someone updating: remove default.conf.
Another way: open default.conf and remove the layout section, carefully, save the file and then open Code::Blocks.
Just another way (without touching default.conf): open Code::Blocks, go to View, Layouts, Delete current. Let it go for Code::Blocks default, close Code::Blocks without saving layout, open Code::Blocks again. It's a bit tricky so you maybe try another combination of Delete layout, set, save until it gets fixed
If you're going to touch default.conf, it's located in "Documents and Settings\YourUsername\Application Data\codeblocks\" (the path may change a bit if your Windows is in another language or dunno where if it's 9x).