Windows 7 Help with hard disk detection

[Mrunal]

Hello guys,
I need some help with my "Windows 7 professional" computer.
My computer is suddenly not detecting external USB hard drive
While trying to fix this issue I came across 2 further issues:
1) The command prompt window when opened closes immediately due to which I am unable to type in anything.
2) Unable to open gpedit.msc (i do have gpedit installed, it again disappears immediately)

can anyone help me out with the above 3 issues please

 

[Trouble]

Boot your computer into Safe Mode.
Does it still exhibit the same problems?
Enable the hidden administrator's account and boot into that.
Does it still exhibit the same problems?

 

[Mrunal]

Thanks Noob..that was really easy and it worked! It has solved the hard disk detection problem atleast.
I am still not able to open cmd or gpedit though...but not much worried about it...atleast currently

 

[Mrunal]

Even event viewer hardly opens for a couple of secs before closing....can hardly view anything in it....