engine error - help

Firstly hi all, im a bit of a nooB and hope to make a home in the editing community :smile: anyhoo im gettin this badboy when i try to run my map, there are no errors in compiling, the map used to work and only seemed to stop when i went klepto-deleto on a whole section of the map, i also crated a displacement surface at that time. any ideas on what ive done?

make sure that the displacement surface is not the only thing between a light source and the void. Light goes right thru the DISP surfaces. So put a slab of concrete under your disp to block off any leaks.

also make sure you are not running the map directly from hammer. You need to compile, then minimize then open HL2 with the -console command. (open the properties for the shortcut for HL2 and ass the line "-console" after what's there. out of the quotes and without quotes around it) then when you get to HL the console will be up type "map and then your map name" and it should open.