No picture.

I dont know if this is the right place to post this, if not please move.
Today i installed the latest build 678 and everything was ok but when
i went back i have no picture either from the ultimo or digital tv such
as BBC1 etc.The only picture on the tv is the menu details,anyone have
an idea what has hapened and are the two linked (sat and digi tv)

Panic over, went back again and all is working except i have lost the backup i did and
will have to install all the sats again.At least there is nothing serious wrong, phew.