When using Lync, Ctrl+Tab will no longer switch between tab windows, and instead just inserts a tab into the textbox. If I just press Tab, it will change focus from the textbox to the font button (the large A), and with that focused, Ctrl+Tab works. But, that makes the effective shortcut Tab, Ctrl+Tab, which is not what it should be.
I've seen lots of shortcut issues posted here, but not this exact one.