http://imgur.com/a/DW8KG

In System Information, under Memory, the memory tab on the left side shows 48GB for available memory, but in the top right corner of the window it shows 24GB. Windows task manager shows 24GB and that's how much I in fact have installed. This may not be a bug, but I'm not sure what's going on?

24GB RAM + 24GB pagefile

the memory tab on the left side shows 48GB for available memory

You're looking at commit charge limit and it's not the same as physical memory (which is the groupbox just to the right of the commit charge).

The commit charge limit is the current pagefile size plus the physical memory available and from your screenshot it's correct... If you look under the physical memory group box; It shows the correct value for the total available memory.