The master boot record (MBR) lies in the first sector, which is used to choose and boot operating system. PartitionGuru will examine MBR automatically when saving partition table and it'll rebuild one automatically when the MBR is invalid. Thus in general, there no need to rebuild MBR on purpose after partitioning a new hard drive by PartitionGuru.
Rebuild You can use this function to rebuild MBR when it gets damaged or you need to clear boot program of MBR. Operating steps are in the following:
Click "Disk" -> "Rebuild Master Boot Record" and PartitionGuru will pop up the message box:
Click "Yes" and PartitionGuru will rebuild master boot record by using its own MBR.