DMRex95vebs DVD recorder fault code u81

DMR ex 95v ebs DVD recorder.
Showing fault code U81.

The device has been doing several weird functions.
Left off for a while, i.e overnight, machine will not boot up at all. I have to switch on/off at mains to wake it up!
Then we have ''please wait'' and ''Hello'' which takes upto five minutes before machine is ready.
Whilst watching a programme in HD via the machine, o.k. for about 30mins then programme turned off dvd display still showed he channel number though.
Had to re boot again, I have re tuned, several times, thinking this may help, no!
The recorder is unreliable, to say the least. REcording is unreliable, will shut down before end, or not record at all in timer mode.
Signal strength is good and reception good .
The device once working, will often not switch off into a stand by mode, and device will display clock and either dvd or hdd light remains on.

HELP!!!!!!!