I've been having the exact same problem. This machine comes ready with windows 8 installed, but I put windows 7 on
anyway, the performance was terrible so I checked the RAM and it says that same crap, 4.0 GB installed, (929 MB usable).
So my HALF solution is to update the BIOS here: HP Notebook System BIOS Update (Intel Processors)
As ALWAYS be careful when flashing your BIOS. this however only gives me 2.00 GB useable, so its not ideal at all, but its better than 929 MB