I used vSphere to expand the size of the virtual disk on one of our Windows Server 2008 R2 servers.
When I went to expand the drive from within the OS per articles such as this one
How to Extend a Disk Partition in Windows Vista and Server 2008
In step 8, when I went to increase the "Maximum space avialable" I was unable to increase the value.
At this point, I needed to use the "< Remove" button to remove the Disk listed, then use the "Add >" button to add the same volume. I am now able to increase the "Maximum space avialable" value to match the space that was listed within the VMware environment.