Sony KV-32S320 CRT TV

This set has developed a problem with "Auto Tuning" . When this feature is activated it tunes the channels then sorts them into order but reverts back to "sorting ch50 --"  then hangs. Consequently the newly added freeview channels cannot be tuned in as the only way is to abort the auto tune. Has anyone encountered this problem or have any idea's as to a solution. All contributions will be gratefully accepted.