It would appear (although unable to confirm for sure) that following a windows update, Windows 7 Pro (running on Sony Vaio laptop) is unable to boot successfully. The boot process starts normally, I see the words 'windows 7 Professional' on a blue background (This is not a BSOD) but that's it. The screen flickers (like a refresh) but that's it. CTRL-Alt Del does not work at this point.
I have tried the following:
1) Full AV scan from a boot disk - no viruses found
2) Using a recovery boot disk to start 'System Restore'. System restore fails - I've tried 3 different restore points
3) SFC /scannow - No issues found
4) CHKDSK /F - No issues found
5) Unable to boot into Safe mode - Same symptoms - blue background with screen flicker
6) Start-up repair - Ran 3 times - problem still exists
7) Memory test - No issues found
8) Sony Hard Drive diagnostics - No issues found
9) Last known good config does not correct the issue
10) Booted into reduced resolution - Same symptoms - blue background with screen flicker
11) No BSOD witnessed
Other than a complete format/restore, what other options are available to identify and correct the cause?