If like me you come across this error while installing wubi, don’t worry theres a really easy and simple fix
If you are using a different computer to view this simple type reboot on the grub command line, once your system has rebooted, boot into windows.
Otherwise im assuming you are already viewing this in windows.
First of all we need to download this file wubildr
Once downloaded copy the file into c:\ and replace the existing faulty wubildr file.
Once replaced restart your computer boot into ubuntu and all will be fine.
Why did this happen you are wondering
To be able to boot Wubi, Grub2 has to access the ntfs partition which is hosting Wubi. There is a bug in Grub 2, which prevents Grub2 to read any files on an ntfs partition beyond the first 4GB. If any of the boot files is outside of the 4GB limit, booting will fail. Depending on which boot file is outside the limit, the symptoms can be quite different. Since any kernel or Grub update relocates some of the boot files, you might be hit by this bug at any time.