I recently downloaded a program that changed my computer SID wich i dont know too much about only that i know it is like my computers identity. anyways it went through changing all my files and folders and thing for a while. now when i click on any other program or file it says acces denied or this file is locked for use of "my name". someone please help me. i want to know how to get my old SID back or change all my files so i can use them again. please respond

Sounds like you might be in trouble. What was the name of the program? Why did you think you needed to change your SID?

is this computer a member of active directory? if so, unjoin and rejoin the domain. otherwise, you could use sysprep to generate a new CLEAN sid. but depending on what this program you ran... who knows BTW, this has nothing to do with exchange 2007. please post in the correct forum.