Error with Mountain Lion Download on the App Store

Hi there, I've come across an error which I've been unable to solve and have not found similar instances/references on the forums: I bought Mountain Lion and started downloading. I have several laptops, so I also started downloading on my main laptop. In the mean time, the first download was very slow and had 9 hours to go. The second laptop, started later, had 30 mins to go. I realized the first one was connected to my slower home wi fi (I have two), so I interrupted the download and tried to re-download it once I connected to the fast wi-fi. When I tried to press download again, I had an error. Next to that error, a "X" (for cancel) came up.

Then, the oddest thing happened and Mountain Lion was removed from my purchases!

After that, I went back into purchases and when I clicked "buy" it just said "You've already purchased this, click here to download". When I did that, I got this screen. Now, nothing happens. I just get stuck here.

I've installed Mountain Lion on the other laptop (the second one) and it seems to be working fine.

I looked online and there was a supposed fix: to download a Lion Combo 10.7.4. I did, but when I tried to instal it, it just said that it requires a version of Lion 10.7.3. or earlier... I have 10.7.4, so this did not work.

Any help?

Many thanks!!!