I fired up CW 10.5 this morning and this popped up.
It worked fine yesterday and I haven't installed any plugins since then so it's a mystery to me why CW is in this unusable state.
I uninstalled and reinstalled but the problem persists which leads me to think that something is wrong with my workspace.
I did start using the Team Foundation Server plugin yesterday so maybe that messed something up but the problem persists without the plugin loaded.
I think making a new workspace will fix the issue but I'd rather not have to keep doing that.
Anyway, if anyone's run into this problem before I'd love to know what caused it.