After resizing a C: partition I'm left with two blocks of "unallocated space". However despite the fact that neither of these blocks is a partition (they're just blank space) Windows sees them as separate blocks. I cannot see any way to combine them or to create a new partition which spans both blocks of free space. See screenshot:
Best Answer
The reason for this is because you are using an MBR disk rather than GPT, the maximum size of an MBR disk being 2TB. This is a bug in the disk management UI as in how it displays it, but functionally you'll only ever be able to use that first segment because of MBR constraints.
The only officially supported way to change this is to either re-install or use windows backup and restore, however there are a few programs available that purport to be able to do it but I don't know what it would do to the bootloader. Take a look at minitool partition wizard and, as mentioned above, GParted.