Are you running your own custom build or an official mojoportal release? What version of mojoPortal?
I can tell you that on a development machine when you make a change to a .browser files the change isn't effective until the project is re-compiled.
My best guess is the file is somehow corrupted. If you're not running the latest mojoportal I would upgrade it and make sure you replace all the files with the new version.
Hope it helps,