Weird memory graph

[rocky2]

http://401.cx/~rocky/sys_memory.png" border=0 alt="http://401.cx/~rocky/sys_memory.png">

Can someone explain how this is possible?
I can understand that memory graphing is not always perfectly accurate, but how the total amount of memory can vary from 300M to 1.6G is something I can not understand. I can buy that it says total memory 850M, for some reason the total amount of memory always come up short when applications try to measure it on FreeBSD, but I simply do not understand this graph.
It seems to miss the same amount of memory that top lists as inactive. Is it simply so that it does not count inactive memory at all?

The machine in question has 1G of ram.

[antoniop]

FYI: I have the exact same issue.  This box has 1Gb of RAM but the graph total reports 791Meg?!
I have confirmed the memory usage on the system in question.

Anyone got ideas why this is happening?

Snapshot:

[matt]

that graph needs some attention, known issue. Basically, someone needs to go back through the SNMP values reported and verify them and my math. I made an error somewhere in there and haven't gotten around to fixing it.