Comment 18 for bug 1042159

I decided to disable "hybrid sleep" in Win8_RTM : I selected "off" in "Allow hybrid sleep" (Control Panel > Power Options > Change plan settings > advanced power settings > Sleep > Allow hybrid sleep ). After that, I tried all ways to leave Win8 (Restart, ShutDown, Sleep) and fortunately there was no problem with Wubi. So, one possible solution is to disable "hybrid sleep".

To complement this information, I checked the sequence described in the preview comment #16 :

1) after using Win8 "Sleep", out of sleep mode and "Restart" : Win8 NOT Hibernated

2) after using Win8 "Restart" : Win8 NOT Hibernated

3) after using Win8 "Restart" : Win8 NOT Hibernated

4) after using Win8 "ShutDown" : Win8 hibernated

5) after using Win8 "Restart" : Win8 NOT Hibernated

6) after using Win8 "Restart" : Win8 NOT Hibernated

We can see that the sleep mode became completely harmless ( step 1 to 3 : the Win8 partition is "not hibernated" instead of "hibernated" in comment #16).
It should be noted that the feature "Fast Restart" was maintained, only "hybrid sleep" was disabled