This problem is similar in nature and most likely identical to bug 653134. The fix was documented in that bug.
Summary:
When updating package grub-pc, it attempts to update the wubildr on /host. It calls grub-install to do this. For Wubi installs grub-install is modified in package lupin-support, and it calls grub-install.real (the actual grub-install script for normal installs). Grub-install also copies all the grub .img, .lst, .o etc. files into the /boot/grub directory. These do not normally exist for Wubi installs, and result in a grub.cfg file being created that is incompatible with wubildr (for unknown reasons).
The fix is to remove all these files from /boot/grub leaving just grub.cfg and grubenv. However, you need to manually modify the grub.cfg to get it to boot first.
The potential fix:
Modify lupin-support's grub-install to clean up the /boot/grub directory.
This problem is similar in nature and most likely identical to bug 653134. The fix was documented in that bug.
Summary:
When updating package grub-pc, it attempts to update the wubildr on /host. It calls grub-install to do this. For Wubi installs grub-install is modified in package lupin-support, and it calls grub-install.real (the actual grub-install script for normal installs). Grub-install also copies all the grub .img, .lst, .o etc. files into the /boot/grub directory. These do not normally exist for Wubi installs, and result in a grub.cfg file being created that is incompatible with wubildr (for unknown reasons).
The fix is to remove all these files from /boot/grub leaving just grub.cfg and grubenv. However, you need to manually modify the grub.cfg to get it to boot first.
The potential fix:
Modify lupin-support's grub-install to clean up the /boot/grub directory.