Bug Check 0x7A: KERNEL_DATA_INPAGE_ERROR
And according to Parameter 2 of the STOP code:
0xC000009D, or STATUS_DEVICE_NOT_CONNECTED, indicates defective or loose cabling, termination, or that the controller does not see the hard disk.
Check your HDD's cables and make sure they're snug/tight.
I'd also suggest running a disk check on your HDD:
Start -> type 'cmd' (without quotes) -> right click -> run as admin -> in the console window that pops up type:
chkdsk C: /f /r
Press Enter and it will say it cannot lock the current drive and to run on next reboot. Type Y and hit Enter -> Reboot your computer and let it run through the check (it may take some time, depending on how big your HDD is).