Alrite guys!!

I have just got my zgemma h2h up and running on my Openatv 5.3 image (needs updating )for virmin but say if I go to a Sly HD movie channel it runs perfectly but say if I turn over to Clubland it freezes loads and screen goes blank for 10secs but will come etc?

I checked the signal finder and mine is SNR: 73% and the AGR: 7%

Any ideas what the problem could be plz guys??

cheers!!