Check your hard disk, it seems to have some bad sectors.
What should I check concretly? My hard disk seems work fine aside from that.
Can you try it on another computer?
Unfortunately no. I really need Bitcoin-qt working on this computer.
Ok I understand you need it working on this computer, however to test can you try it on another computer first? As this would rule out so many things, one way or the other.
Check your hard disk, it seems to have some bad sectors.
Good advice, maybe do a /chkdsk of your hard drive.
http://en.wikipedia.org/wiki/CHKDSK