I had a similar problem on my PC before reinstalling.....

After reinstalling it came back!! I presume it's down to some update clashes.

I fixed it though and posted this text on another website....hope it helps!

I've had this problem on my old set up and it just occurred sometime but I was unsure Why or How????

I've recently did a full install and one of the first things I checked was this strangeness and all worked fine!!

I've been on the new install for several weeks and had the NSIS error and the corrupted file thing also but managed to deal with them. Bloody Nvidia and it's firewall that I'm sure I didn't select!

Finally got it all working video stream wise (surprised at no answers on the web though??)

I uninstalled my motherboard drivers from change programs, uninstalled my anti-virus etc. (McAfee), uninstalled my video drivers and took a bit of time to reinstall them (partially) without anything else (didn't see anything strange though!!).

I didn't install my McAfee firewall and ignored the 2 way thing when prompted and then made sure my windows firewall was enabled.

Low and behold it all works!! took me about 4 hours though using various combo's until it worked?? Set yourself a night aside and try it or a number of combos!!

Good luck on this as I only registered to try and help you as I'm not that techy! well I can build and play with them.... Again good luck as it's damn annoying!