Node Graph Out Of Date. Rebuilding..... (Please help!!)

Ok, Whenever I load-up a map besides gm_construct, I always get something saying, Node Graph Out Of Date. Rebuilding… and the map is all glitchy and game play goes REALLY slow.
can any1 help?

Hmm. I know for a fact that when the message “Note Graph Out Of Date. Rebuilding…” is up, the game is frozen. After about 5 to 10 seconds, it goes back to normal. If it’s a large map, it may stutter for 5 additional seconds. After that, it’s smooth.

Care to list the specs?

delete maps/graph

Now, when you start one map, this will appear one time again. When it’s finished (takes a few seconds) it will never appear for this map again.

HL2, like HL1, uses a “node”(waypoint) system for AI. Normally a map is accompanied by a .nod file, but if such a file doesn’t exist, HL2 will build the .nod file itself. This doesn’t normally take longer than a few seconds or minutes.