Windows 7: Computer suddenly ran slow, now boots up to black screen

Hi. Last night I ran into a black screen problem on Windows 7; I did install the latest batch of updates on the 13th (I had 13 ready to install before shutting down) *and my computer ran well for most of yesterday, but suddenly it began running extremely slow. I was unable to shut it down in a timely manner as it had crashed, I forced a shut down by manually pressing the power button.*

I restarted my computer and found that explorer wasn't running despite the login screen showing up and being able to move my cursor. I ran a search on my phone and found that it's a common issue, but my attempts to fix them have been futile. I burned fixshell.exe on to a disc through a family member's computer and it booted up on my computer but didn't fix it. Explorer doesn't run so I can't end the process, and I tried running it but I get the prompt that my Internet security settings are preventing it from running. Is it possible that the security setting is the root of this issue, and is there a way to whitelist explorer.exe through the task manager?



Safe Mode gives me a similar condition; the desktop is black (sans the 'safe mode's in the corners), Fixshell boots up but doesn't repair the problem, and manually running Explorer triggers the Internet security block.

I tried the key combination of Winkey-right-right-enter with no success; I haven't used the Winkey in regular use so my best assumption is that it's not tied to sleep mode.

I attempted a system restore from multiple points before the latest update was installed, and I received the following error though the attempts initially said "finished":

"System Restore did not complete successfully. Your computer's system files and settings were not changed.

Details:
System Restore failed while deleting the following file/directory.
Path: D:\
An unspecified error occurred during system restore. (0x8000ffff)"

I was initially led to believe that D:\ is my DVD/CD drive, as it's the directory that boots when I run a disc, but the System Recovery menu lists my OS drive as D:\ whereas System Restore listed my OS System Directory as C:\. It's left me a little confused myself. I also found out that my father incidentially had the same thing happen to his laptop (a different manufacturer and runs on Vista) last night as well.

Unfortunately I don't know my full system specs- it's a Dell Inspiron purchased from Best Buy (but is no longer under warranty) and I believe it runs 32bit Windows 7 Home. If the info I provided isn't too little, I would definitely appreciate any help.