Warning Message: 

The publisher could not be verified. Are you sure you want to run this software?

I got this warning message last week while testing a group policy object to run a small program from a network drive when users log in to the domain.

After some googling, it turned out that this feature was added in Windows XP Service Pack 2 and it checks whether the program has a digital signature attached.

To prevent this from appearing do the following:

1. Open the Group Policy management console (Start->Run->gpedit.msc)
2. Go to User Configuration->Administrative Templates->Windows Components->Attachment Manager
3. Enable “Inclusion list for moderate risk file types“
4. Add .exe to the list

Source: http://davestechshop.net/archive/2006/10/30/IE7PublisherCouldNotBeVerified.aspx