Stubborn laptop - boot issues

Recently, my sister dropped off her HP Pavilion dv6 laptop. She told me it had a few viruses that were quarantined...but couldn't be removed. Her school requires Symantec Endpoint Protection to be allowed on the network...so I wasn't surprised that the infections couldn't be completely removed. She didn't have the power cable with it at the time, so while waiting, I removed the HDD, plugged it in to my computer using an external USB Thermaltake dock. I ran MSE on the drive, and it found three viruses, including one listed as a boot virus, and successfully removed them. A second scan came up clean.

Now, here's the problem. I put the drive back into her laptop, and it won't boot. I get to the Windows 7 splash screen, and after the glowing orbs circle around, it blue screens. This happens under a normal boot, and all safe mode options.

I ran the various start up repair options, everything from the actual start up repair, to the bootrec commands, to sfc, etc....each several times in a row without any luck. The partitions are detected and accessible, but won't boot. What else can I try? My last step is going to be to image the drive and start over, but I'd like to avoid this.

When you put the drive back back in your sister's laptop, is it stilled mapped to drive letter C?

Does it still hold the active flag?

Have you tried the F8 key at startup and choosing Last Known Good Configuration?

According to DISKPART, the drive may be mapped to D...the system volume. I know it wasn't like that before.

I've also never had to set a partition active in 15 years of troubleshooting...so would that cause an issue like this? If so, what's the best way to change this?

What diskpart sees is not necessarily what the host computer would see. Take a look at the partitions and you'll probably see a small one, around 100 megs, which diskpart will call C and a second partition, much larger, that diskpart will call D. You may also have another partition on the drive if the laptop came with a recovery partition, which diskpart will probably call E.

DISCLAIMER:
I am assuming you're booting to either a Windows PE disk or using the console from the installation disk.

What you do next depends upon whether my assumption is correct or not, so do let us know.

You are correct. I'm booting from the Windows 7 install disc into the console at the first title screen. (Shift + F10).

You are correct on volumes as well. I can tell by the sizes that the system utility partition is C, the actual system volume drive for Windows 7 is D, and the OEM recovery partition is E.

Is that any different than the bootrec /fixmbr command? I've run that several times with no luck.

Have a look at this tut: Partition - Mark as Active

And this one: Partition - Mark as Inactive

And finally: Startup Repair - Run 3 Separate Times