Why wil my Pace DS430N not retain channels stored in "Other Channels"?

I have a Pace DS430N digibox. However when I store channels in the "Other Channels" under the "Services" menu they disappear when I press an interactive service like Sky News Acitve, BBCi, etc. I borrowed a friends 430N and carried out the same test. This worked fine. What could be causing this issue with my DS430N? Any help would be appreciated.

Many thanks