Computer in question: Dell Studio 1555, purchased in July 2009 (Service Tag BMBR7K1). Came with Windows Vista; upgraded to Windows 7 Home Premium ASAP. I have kept Windows 7 updated whenever Microsoft put out an update. I updated the BIOS to A11 about a month ago. Except for some minor issues, this computer has been running fine since updating to Windows 7 late last fall until a couple of weeks ago (when "McAfee" starting to produce strange symptoms).
Recent history: McAfee Security Center was (automatically) updated ABOUT two weeks ago. After that some Windows tool in the taskbar consistently told me I had no antivirus protection and all McAfee dialog boxes were visually empty. I decided to uninstall the entire McAfee package, then install a new copy. All normal uninstall routes failed; a basically blank McAfee dialog window would come up, but I could go no further. I finally resorted to using the Revo uninstaller. It also failed to uninstall the program, but then offered to remove any remnants of the McAfee software, including registry entries. I instructed Revo to delete any and all renmants it found. That was apparently a BIG mistake! I am assuming it removed or altered registry entries vital to basic Windows 7 operation.
What I get now:
I can turn the computer off ONLY by removing all power OR holding the power button in for at least five seconds. It turns on with just a brief press of the power button. I then get the screen telling me the computer had not been turned off successfully OR a screen which is entirely black except for a small mouse/touchpad cursor, depending on the way the computer had most recently been turned off.
If, from the "not turned off successfully" screen, I select "start windows normally" I next get the black screen with a mouse cursor. If I select "Safe Mode" or "Safe Mode with Command Prompt" I get many lines printed on the screen starting with "Loaded". The final Load is of \windows\system32\DRIVERS\CLASSPNP.SYS"; after another five-ten seconds I get the black screen with a large mouse/touchpad cursor.
I have tried booting from the Windows 7 upgrade DVD supplied by Dell last October, choosing the "Repair Your Computer" option and then selecting Windows 7 (the only choice) as the operating system.
The "Startup Repair" option detects NO problems.
"System Restore" seems to work normally, but choosing an earlier Restore point does not fix the problem
"System Image Recovery" is not a possibility for me
"Windows Memory Diagnostic" does not tell me about any problems found
"Command Prompt" allows me to navigate anywhere I want on the C:\ or D:\ partion, as well as on the DVD.
I tried running System Mechanic Professional 10, to see if it could detect what the fundamental problem is, but it seemed to lack the necessary drivers to be able to access the hard drive of the Studio 1555.
My analysis is that all hardware components of the computer are working fine and that the non-system hard drive contents seem to be intact, but that some critical part of Windows 7 (probably the registry) is damaged severely.
HELP! What tools/techniques are most likely to help me restore Windows 7 without harming my installed programs and especially without harming my user data?
(I have looked at all the responses to ID: 26413565; none of them seem to fit my problem.)