Which version numbers does the console show in Settings/Ressources?
Which security suite is installed on the Vista-PC?
The best method to resolve such issues, which have no deeper background, could really be to uninstall the connector software from the client, reboot, delete the remains (if there are any) in C:\Program Files\Home Server Connector Software and install it again from
http://server:55000 or from the Software share (in folder Home Server Connector Software run setup.exe).
Best greetings from Germany
Olaf