If you have SCCM installed and you have an advertisement that has no manditory time then the user will see it in the Run Advertised programs (or add/remove depending on their settings) An issue has occured that if you are running in a locked down enviroment you might have a problem when sending advs down. We have our systems locked down so only a very few systems have Admin Rights. Even the IT dept runs with limited rights. We only use our admin account when necessary. The problem arises if you have this situation:
User only mode
No Manditory time on Advertisement
No Network Access Account
Bits 2.5 will fail at 99% or just not even start. Even though the Access Account is not used it prevents the download from occuring. When the same settings are used with an admin the problem is not seen. The solution is to configure a user account for use as the Network Access Account and downloads will work. Hopefully this will be fixed in the SP1 that should be out First Quarter of 2008