BasePortalVis:
(3.20 seconds)
Warning: Leaf portals saw into leaf
Problem at portal between leaves 118 and 119:
(1270.859 678.999 504.001)
(1280.000 672.148 512.000)
(1279.903 672.074 512.086)
(1016.000 672.074 512.086)
(1016.000 678.999 504.001)

Warning: Leaf portals saw into leaf
Problem at portal between leaves 133 and 131:
(392.000 687.927 656.145)
(392.000 684.001 648.001)
(639.720 684.001 648.001)
(644.001 685.929 652.001)
(648.145 687.927 656.145)

Warning: Leaf portals saw into leaf
Problem at portal between leaves 443 and 444:
(599.871 -1472.207 768.207)
(600.000 -1472.393 768.000)
(597.500 -1476.000 764.000)
(224.000 -1476.000 764.000)
(224.000 -1472.207 768.207)

average leafs visible: 433
g_visdatasize:48148 compressed from 50640
3.31 seconds elapsed

Can someone tell me exactly what might cause this error and how I can fix it.

Please. :confused:

they only time I had this problem was when I was begining to map. what caused it for me was that I had very complex brushes overlapping eachother.. so check to see if you have any overlapping brushes.. If not then I dunno..

Overlapping brushes = nightmare ;/

It's actually not an error, just a warning.

Leaf saw into leaf is simply when a brush has to sides facing each other.

Imagine a brush like a V, the inner sides of the V are facing each other and would cause a leaf saw into leaf warning.

Atleast thats what I been told, so I hope that correct. :D

Since it just a warning it can be ignored but if you get to many it can mess up your rad or vis, if I remember correctly...

As always, tommy14's webby might be able to help you:
http://www.slackiller.com/tommy14/errors.htm#leafsaw