I don't think it's your MB. Sounds more like a disc issue.
Run repair from your windows dvd:
1. Insert dvd in cd/dvd tray, shut down computer
2. Restart and access boot manager (on my Asus boards, I press F8 until the boot choices appear
3. Boot from your cd device - it shoud say cd/dvd/rw or some such
4. Press any key to boot from cd
5. Windows files will load, and windows start up screen will appear
6. At start screen, choose "next"
7. Choose Repair your computer (lower left side)
8. Choose your operating system and press next
9. At the choices screen you have several options, of which three will be your best choices:
a. Startup repair - this will automatically check your complete startup method, drivers, disc, etc. This may take some time to complete, so be patient, or
b. System restore - If you know you have a good restore point (prior to when you started having problems, this choice will "reset" your pc to the condition it was in on that date, or
c. Command prompt - this choice puts you on the command prompt line where you will enter dos commands. In your case the command would be "chkdsk" without the quotes. I do not recommend this unless you are comfortable working in dos. If you go this route, it will take quite some time to complete.
IMO, your best bet would be to try the startup repair first and see if that fixes the boot issues. If you are able to boot into windows, DO NOT run and programs immediately - just let it sit for a couple minutes to see if anythings burps. If it seems to be running right, click the start button and in the search box type "cleanmgr.exe" without the quotes and run that program to clean up loose junk.
If the startup repair doesn't work, then try the system restore.
If they both fail to get you running right, I suspect your hard drive is dying. If that's the case, remove the old drive and replace it as soon as possible, do a fresh install of windows (with only the cd/dvd drive and new hard drive hooked up), do all the updates, install the anti-virus of your choice (I use microsoft essentials, but then I'm very careful with surfing and emails). Once you are set to go, set up your old hard drive as a secondary (d
drive and recover all your data, photos, files, etc. and store them on your new drive or burn the data to dvds.
Hope this gets you running - let me know if you need any other help.
Mark