grub2 update fails

Hello,

I am not sure if this is a question or a bug. I am also not sure if it has anything to do with Systemback so I apologize if it does not. I installed the system I am running with Systemback. Ubuntu 15.04. Running the newest Systemback in the PPA.

Ubuntu just got an update for Grub2 and during the update it stopped to say the following:

"The GRUB boot loader was previously installed to a disk that is no longer present,
or whose unique identifier has changed for some reason. It is important to make sure that the
installed GRUB core image stays in sync with GRUB modules and grub.cfg. Please check
again to make sure that GRUB is written to the appropriate boot devices."

It offers me 3 choices

The first one in the list is my main hard drive, next is the correct one but it is displayed with a minus in front as shown below, and last is an external hard drive connected by esata.

/dev/sda (500107 MB; WDXXXXXXXXXX)
-/dev/sda1 (14998 MB; /)
/dev/sdb (500107 MB; STXXXXX)

When I choose sda1 or sda, it asks if I want to continue without installing GRUB. If I choose sda and sda1, it says:

"Writing GRUB to boot device failed - continue?"

If I type "fdisk -l" I get the following:

Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 29296639 29294592 14G 83 Linux
/dev/sda2 29296640 35438591 6141952 3G 82 Linux swap / Solaris
/dev/sda3 35438592 976771071 941332480 448.9G 83 Linux

However, when I go to System Monitor in Ubuntu and choose the File Systems tab it shows this:

Device Directory Type Total
/dev/disk/l / ext4 14.6
/dev/sda3 /home ext4 474.3

My PC uses bios, not uefi.

Currently my machine is sitting with the update screen still there because I don' know what to do. Not sure if I should continue without installing GRUB because it says my PC may not boot after.

Any help would be greatly appreciated. Systemback is AMAZING :)

Thank you,
John