This has been a problem for a while and has only been resolved via MS technical support. Plusnet tech support eventually identified that IE, which you have to use to instal Plusnet protect properly, was the problem, but the issue with IE was that Google desktop had corrupted IE.
So the solution turned out to be simple - uninstall Google desktop - but took hours of Plusnet + MS tech support's time and ££ (with MS).
So BEWARE Google desktop messing with your security
