Strange memory problems

[Eugene]

Hi people,

I have a strange problem with memory.
System is FreeBSD 5.3, 4GB physical memory.
Even in very quiet load, memory allocation statistics looks like this:
last pid: 38330;  load averages:  0.67,  1.05,  1.03  up 6+06:50:14 
15:52:30
159 processes: 2 running, 156 sleeping, 1 zombie

Mem: 757M Active, 2673M Inact, 220M Wired, 107M Cache, 112M Buf, 7000K Free
Swap: 10G Total, 1884K Used, 10G Free

That is, almost 3GB of memory is Inactive while free memory is almost used 
up.
If I do 'ps axvf' and sum up the memory columns, I get RSS=1.5GB and 
VSZ=1.9GB (approximately).
With Apache stopped, it goes down to RSS=0.5GB and VSZ=0.6G -- but Inactive 
Memory remains above 2.5GB.
Is it a memory leak somewhere or what?

Thanks in advance
Eugene