It’s possible that there is another extension that is conflicting with CabWriter. Copy or ZIP your entire Plugins folder and move to another temporary folder. Then, one at a time, remove other extensions besides CabWriter from your Plugins folder, close and reopen SketchUp and see if it helped. Doing it one at a time will uncover the conflicting extension, if there is one. If this doesn’t help give me a call at 413-961-9115.