Steam - Error [HAAALP!!]

Ok, so I have four computers at my house. One for me, and each of my two brothers. We decided to buy the 4-pack of Borderlands on steam considering, we had to buy 3 anyways, why not get the 4th free.. 

So the game is up and running on 3 of the 4 PCs. I cannot get the to work on the fourth tho. it keeps saying:

"This game is currently unavailable. Please try again at another time."

I have googled the problem with no good results... I have tried everything that I could find that has helped other people on other forums but to no avail... I've resarted my computer, restarted steam, reinstalled Borderlands, reinstalled steam, updated drivers, update everything... ive done everything! PLEASE HELP ME..