Hi kaznz.
Try updating your java, that may help then make sure XP firewall is off
Now! Go to,
START/Set Program Access/Change or Remove Programs,
now completely remove all versions of java.
Now! Use this Link to get JRE 6 Use the off line installer NOT the (recormended) one,
http://java.sun.com/javase/downloads/index.jsp
Disconnect from internet, close ALL apps n reinstall java.
Follow thease instructions exactly.
P.S.. Ive spent time trying to find info on your Dynalink UD800G3 Home ADSL, N man Im lost on that one.
If you have an instalation CD for it, Put it in and look for a setup Doc. to configure settings.