Bishy, I think the issue is earlier,
There's 2 things that come to the top of my head
1. Anti-Virus programs tries to scan it, takes pretty long time due to being close to 1gb of content in it.
2. I forgot...
I'd recommend TEMPORARY turning off your anti-virus program. And see if that works better, also try to "run as admin" by right clicking on it.
Please also check the the "HDD LCD" (normally in front of your case, below of "computer is turn on LCD"), is glowing more or less (if you are on a Desktop Computer that is, laptops normally have this icon near the battery LCD). If it's glowing, it means your computer (hdd) is processing it. A semi-corrupt download could cause (I think this was the 2nd thing I was thinking off above) this I guess, or just a slow(ish) HDD.