Cannot Install Ubuntu - no option to install Ubuntu alongside Windows
Solution 1:
Your problem is almost certainly caused by leftover GPT data on an MBR disk. You can correct this problem by running FixParts (part of the Ubuntu gdisk
package) on the disk. Once you've done that, you should be able to resize partitions to make it all work.
Also, be sure to disable the Windows 8 Fast Startup feature. This feature is incompatible with a dual- (much less a triple-)boot configuration.