Jase2985:

 

Do these machines have issues accessing stuff?

 

No, they can both access Stuff ok. And I've just discovered that my main pc, which is also running W7 Ultimate, also has no problems with Stuff. So it's just this one W7 laptop that has an issue. Actually, this machine has another odd glitch. Generally, if I'm browsing on any computer and come across several websites of interest, I'll usually just right click each one and select 'Open in a new tab'. Finally I'll left click on each of those new tabs in turn to view them. But on this laptop, when I do this, I'm informed that I've been redirected to another link and have to click that to get to the page. 

So there's obviously something corrupt in this Firefox installation. Maybe it'd be quicker to just wipe the install and start over.