MBR is the Master Boot Record and track o is also part of you operating system. It is possible that they are separate partitions on your hard drive for doing OS repairs. It is also possible that they are the partitions on which your OS is stored for security reasons.
If it is the latter case then to do a full restore of "C" drive you should have also imaged those two partitions to capture the OS. If I am right then it could explain why the Acronis restore in your other thread was looking for the OS. Your PC manufacturer should tell you which is the case.