That shell32.dll is for SP1 so if you dont have it you might want to change back to the windows original. Another thing is how did u change the files? Did u just do it from a regular user or from Administrator in safe mode?
Yeah, if you do it from a regular user windows will change it back as soon as you replace so safe mode is the only option. There is a replacer program that lets you do it from a regular user and it makes a backup but I dont have a link.