I had a blue screen the other day on a Win7 PC, followed by 2 reboots overnight. Then today I found that Event Viewer would not display anything. So I checked in Services and found the Event service was not started and would not start, it gave Event Log Error 4201 which when Googled led me to check the security properties for the RtBackup directory, I found that the SYSTEM group was missing from the groupm permissions so I added it and restarted.
On restart it asked for the install disk and gave a status of 0x0000225, and said "The boot selection failed because a required device is inaccessible". Start Windows normally failed as did Safe Mode and Windows repair.
I tried running GParted on an Ultimate Boot CD but that showed a libparted bug found - Input/Output error during read on /dev/sda. I then ran GSmartControl and the short test completed without errors.
I then put the drive into a usb caddy and inspected it in a Windows Vista PC where it correctly showed the 2 partitions. I ran a check disk in computer disk management and it detected and fixed some errors.
I then ran diskpart to check if the OS partition was 'active' but that flag was not listed. I also inspected the disk using AOMEI Partition Assistant which indicated that the disk is GPT not MBR. Does the OS partition need to be set to 'active' whether it's MBR or GPT? I assume so. AOMEI Partition Assistant wouldn't let me use the set active function, maybe Pro version needed. Can I set active using Diskpart when the disk is a slave in the usb caddy? Or can I somehow run Diskpart on a bootable CD or USB stick when the drive is installed?
What else should I do to repair a GPT disk when the Windows Repair disks won't run?