dreambox 800se freezes when i try to turn the channel over

[Kezzakamkam]

i have a dreambox 800se it freezes everytime i try and turn the channel over , now when i first had the box my friend set it up for me he had a few probs when he was installing the bouquets id have tv chasnnels but as soon as the bouquets was in it was saying tuner error and i had nothing he then took it home and got it working with the bouquets but after 2 days i noticed we cant turn the tv over without it freezing and havin digital worldz at the top left hand corner coming on and whilst this is on it wont do a thing i have had a look at the box and it says enigma 2 n a sim 2 and these are what ive found in the settings so far
image digitalworldz v 1.1
openpli 2.1
kernal version 2.6.18
enigma aril 14-2012
can anyone help me as ive contacted him and he doesnt know what to do and its driving us nuts now
im totally new to this so explaing what i have to do would be a great help thanks