According to Toshiba Support, they say error is due to a corruption in the recovery partition on the HDD.
If you didn't make a set of recovery optical discs, you can order them from Toshiba. The order form for European models is here: https://backupmedia.toshiba.eu/
Please bear in mind that if the corruption of the recovery partition was caused by a failing hard drive, the drive should be replaced before running the recovery discs.