The Dell PC restore partition (Ctl+F11 on startup) depends upon at least two things to work:
1) No modification to the hard drive's master boot record. A modification occurs with Acronis Secure Zone as warned in the TI8 user manual. (THIS WARNING IS TOO SMALL AND TOO VAGUE.)
2) No deletion of the Dell PC restore program that resides on the C partition.
If you inadvertently modify the MBR with something like Acronis Secure Zone or Partition Magic, etc. you will lose the functionality of the Dell restore partition.
If you reformat the C partition or otherwise delete the Dell PC restore program (listed under add/remove programs in control panels) you will lose functionality of Dell pc restore. Ctl+F11 will no longer work.
You cannot restore it to functionality by fixing the MBR. Once it's dead, forget it. Even if the restore partition is still present on the hard drive, it will never work again.
That's why it's so important to clone or create an image of your hard drive and store it safely somewhere other than on the hard drive you want to protect. That's the only way you're going to be able to restore the functionality of the Dell PC restore partition if your drive is corrupted or fails.