I'm almost there! Struggling to get past this though. I've tried running as administrator, compatibility modes, I've allowed it in my firewall and I've exempted it from windows defender. Googling yielded no useful results also. Ps. You've no idea how annoying it's been to even get to this stage... DO NOT EVER GET WINDOWS 8.
Try closing everything in the background. Especially MSN, Windows Live Messenger & Skype and try again.
Didn't have any of those programs running, but I closed everything as you said (Spotify/Steam/BBC iPlayer/Windows Defender/Google Chrome/WinRAR) and it loaded! Thank you! Is there problems running it alongside any of those programs do you know? I would be nice to know exactly what the problem is, if anyone knows, so I don't struggle running it in future.