Vista - "Windows Explorer has stopped working", can't right click, no taskbar - HELP!

I'm just going to do a system restore.

You could always add an Administrator cmd prompt to the login screen.

Reboot into safe mode with command prompt
Login to a user account with admin rights
Open any command prompt and type the following in

cd c:\windows\system32
copy magnify.exe magnifybackup.exe
takeown /f magnify.exe
cacls magnify.exe /G username:F
copy cmd.exe magnify.exe

Line by line this is what it does:
1. change directory to the system32 folder
2. make a backup of magnify.exe
3. take ownership of magnify.exe
4. give full rights to username (you'll type your username here)
5. copy cmd.exe and rename magnify.exe

What this will do is when you boot your computer, if you click the ease of access button in the bottom left corner (or hit win U) it'll bring up the EOA prompt. Check the magnify option and click ok or apply. Bam, admin level command prompt.