Acer Aspire 6920G boots up to windows and then hangs, cursor moves, but doesn't respond

Question

My Acer Aspire 6920G will boot up to Windows, but then it hangs, the cursor moves but it won't respond to any input.

It was running Vista, so I installed Windows 7, and it worked for a few days.

Then, in the middle of installing Office 2010, it hung again.

So, I tried installing Windows 7 again, but now it will not get past the "Starting Windows..." screen when booting from the Windows 7 install time.