deltree *.* only deletes all files within that directory so everything up or down from the specified path would go uneffected. System files won't be touched and neither will global libraries since so many processes use them at once. You can't delete running applications either. You wouldn't be able to automaticly delete read only and hidden files... even as admin.

I've explained this to you on more than one occasion... we've both been using computers for how long?!