For a patch/workaround:
A) get the wubildr in https://bugs.edge.launchpad.net/ubuntu/+source/grub2/+bug/477104/comments/90 and copy it over C:\wubildr
B) ensure that when you boot there is no command "insmod ntfs". Press "e" at the grub boot menu to edit the relevant entry and remove "insmod ntfs" before proceeding
New ubuntu/wubi installations do not contain the patch yet. The patch will only be applied once there is a clear confirmation (from you) that it actually solves the problem. Hence your feedback is appreciated.