Channels won't clear on boot or after going into menu settings problem

[lumberjack]

Hello.

Have been given an 800hd to try and playing with it has sprung some problems as follows.

Yesterday a channel would scramble after about 8 seconds and them come back on again 8 seconds later.
This went on continuously for about 30 minutes regular as a clock. (I left it on that long to check fully)

Today I have noted that it stayed on for a few minutes without scrambling so I went into setting and started
deleting some foreign stuff that had been left on from shop owner.

On coming out of the menu it would not clear.

Going in to supersetting and pressing test it connected and cleared.

I went into menu and deleted a few channels again then back out showed scrambled again.

So I went into supersetting and pressed test and it connected and cleared etc etc.

I have just now switched the box off and back on and it scrambled, needing me to do a
yet another test connection on supersetting.

Weird but consistent.

Firmware on the box is.

dvbs_evb_Vo3
S/W R4750
F/w 1.0.16777216-5379215
Jan 11 2012

Hope someone can help

thanks

ps this says it's my first post yet I have introduced my self an hour ago in the correct section.