WSUS client not reporting to server

I have looked at several forum entries, as well as information on the MS web site, but have not found the answer to my issue. Our Company distributes automatic updates to the local client machines (using Windows XP Professional) through a site WSUS server. This works quite well in most cases, but I have found one machine that will not talk to the server. In trying to find the root cause of this issue, I found TechNet bulletin that explained where to look in the Registry for the settings to let the local client know where to find the server, etc. On the machines that are working, these settings are all set the same. On the machine that is not communicating, something must have happend because NONE of the settings are present in its Registry.

I have been trying to find a way to reestablish these settings, but have not found the right course of action. Any help on this issue would be greatly appreciated, since the only other course of action I have been given is to reimage the machine, which I don't want to do unless ABSOLUTELY necessary!

Thanks for your insight into this issue!