Windows 7: Relatively new laptop: sudden crash and very slow reboot

For the record, my laptop is a Lenovo B570 that I bought last July. It's running Windows 7, 64bit from what I know.

Yesterday, it was running vastly slower than usual (as per the previous half an hour of use), so I thought to reboot it. Bad idea on my part. It got to the "Starting Windows" screen (without the logo appearing) and just stopped.

I restarted the computer and tried to go into Safe Mode. No go. It hung after a process that it apparently doesn't normally hang up after (I googled the process and found almost no results).

I created a boot CD off the other Windows 7 computer in the house, and tried that. It would only go so far as to ask what kind of keyboard I was using and would stop after that.

I tried using the startup repair option, but the screen would go black and stay like that for several minutes.

After being thus frustrated, I just let it stay on the black screen from startup repair. After perhaps half an hour, the actual repair screen popped up and began running. I was delighted that something new was happening, even if I didn't know if it would help.

After leaving the startup repair up overnight, it told me to reboot the computer. I did so, and after a couple of hours, it finally managed to get to the login screen.

Since then, I have been trying to figure out why it refused to boot as well as why it was responding so slowly. CPU usage was minimal, and physical memory was about 34%. AVG detected nothing wrong, when I ran it before the original shutdown. It refused to start up once my computer was booted again.

I tried sfc /scannow, both the regular and offline versions, but neither would work. I am currently in the midst of restarting my computer to try to run a chkdsk.

I've been searching all over the Internet to try to find a solution, but no one seems to be having the precise problems that I am. Help, please?

(I am a college student and will be leaving tomorrow night. If my laptop is up and running before I leave, I will be rather delighted, but if necessary, I can take it to tech support on campus. I have heard that their skills are lacking, so I don't want to take it to them if I don't have to.)

To update: I ran the chkdsk on the C drive, and nothing was found. I am in the middle of a chkdsk on the E drive, which looks like it'll be a while in finishing.

Still no suggestions?