windows automatic updates on clients

I have Winsows automatic updates server installed on win 2003 server, the WSUS server succusfully sycn and pulls the updates from microsoft site, when i try to install the updates it tells me its been pushed to the clients. when i go to the clients it tells me 10% has been downloaded on the yellow shield, once i click on the yellow shield it seems to disapear, it just seems to be hanging on the 10% mark. what could be the cause. can anybody help me on this.

Regards

Maqbool Patel