> The fact that two of your systems behave so differently should be a red flag - they have DLLs carving up the address space differently, preventing a contiguous 1GB range from being found. DLLs that are part of the Windows OS itself won't vary so much, so you have to wonder what 3rd party DLLs are active on your machines.

The important question for the OP is what the address space of the process really contains and what causes that. The vmmap utility [1] could be used for that.

Cheers,

V.

[1] https://technet.microsoft.com/en-us/sysinternals/vmmap.aspx