But what if the run command is “disabled by your administrator”?

Simple. Works for both XP and Vista(and most probably ancient versions of windows too! )
Go to: C:\Windows\System32 (if C is your installation partition)
Open gpedit.msc
Click on User Configuration > Administrative Templates > Start Menu and Taskbar
Find the entry that says “Remove Run menu from Start Menu”. Double click it.
Change the value to “Enabled.”
Done! Now you can do the rest of the troubleshooting!