"Recording is stopped because of an unexpected error"?

2 progs set to be recorded at the same time now show a symbol explained as above on P43 of handbook. I cant play or delete the progs and so unable to do anything. There seems to be no other ref to this symbol in the handbook. The hard drive has loads of capacity, so perplexed as to why this has happened.

The recorder "locks up" periodically - nothing responds, so turn power off/on to reactvate. A colleague has the same problem.

Any advice would be much appreciated