Windows 7 random unexpected shutdowns, cannot find cause

You did buy a battery which is meant for your exact model, correct? Always cross-check several different ways to make sure the model number of PC, model number of Battery, etc. match. If in doubt ask back here as there will be someone who's done it before.

If the battery ruined your mobo then I doubt it would run.

If Win7 stops working then the next steps are here for Troubleshooting Windows 7 Failure to Start

To make sure you have a perfect install in the first place then stick very closely to the steps in Clean Reinstall Windows 7 which has been used by over a million consumer without a single complaint.

AddRAM said:

You can go through all that or have a proper install of windows in 15 minutes.

Mathew, Bad sectors on a hard drive cannot be repaired.

Hi Addram, your above statement in case of physical sectors is correct, but yes in case of logical sectors, it can be repaired. I have repaired the logical bad sectors of my 1 TB hard disk and now it is working perfectly.

Sir George said:

AddRAM said:

You can go through all that or have a proper install of windows in 15 minutes.

Mathew, Bad sectors on a hard drive cannot be repaired.

Actually, it's a yes and no. It depends on the type of bad sector, physical or logical. See the following link for further details;

Bad Sectors Explained: Why Hard Drives Get Bad Sectors and What You Can Do About It

Exactly true Sir George.