I turned off my computer last night, and I never usually do.
But now when I started my computer it logs in on its own, and I get an error message taht I Was unable to copy and paste here.

Also when I go to use the "Window+L" feature to switch users it won't let me. And it always had before. Another thing is that I cant turn off my computer or log out manually by going to my start menu. The only way to "log off" at the moment is to turn off my computer.

What's going on and how can I fix this?

Oh I also have all the setting in "user accounts" enabled for switching users and the welcome screen.

if u r not installed any software since this problem is installed
Then u can Restore Ur system to earlier Time when ur pc is Working properly
i think its work
Notice:Which date u choose to restore remember any software which is installed after that date will be not Working.
Start>Program>Accessories>System Tolls>System Restore

Its only Restore UR System Files
Ur Friend Indian

well...till you fix the problem you can try logging off from the command prompt :

start >> run and type in cmd

then type logoff and hit enter