few questions about loive tv in medai centre on xp media centre 05

  1st question about media centre is this error i  keep gettign when trying to
watch channel 4. it shows it for a bit while stuttering then it just stops &
gives this error
(http://img131.imageshack.us/my.php?image=errorwj6.jpg )
however i can go to the guide & choose a channel again & it will be fine
pick c4 agian & it will do the same
2nd question is about media centre finding services but not assigning a
cahnnel number to them so they cant be viewd or even add listings to them
(http://img411.imageshack.us/my.php?image=channel4missinsm1.jpg )
i tried re scanning & nothing happened.only thing i can think off doing is
deleting all services then rescanning btu dont wanan do that.
my set-up can be found here
http://www.pcservicecall.co.uk/layout.aspx?CatID= &ID=
with the latest drivers i think