Garrrys Mod Is missing Hl2 Maps

If I go to start a new game and click and Hl2 related maps, it fails to load and this shows up in the console-

CModelLoader::Map_IsValid: ‘maps/ep1_c17_05.bsp’ is not a valid BSP file
map load failed: ep1_c17_05 not found or invalid

http://www.facepunch.com/fp/emoot/wtc.gif

By the way I’m running Gmod on a mac

-snip-

Do you have Half-Life 2 Episode One installed?

EP1 is something else than HL2.

Do you own HL2 on steam? The source engine doesn’t include the HL2 scenes, just models, materials and sounds.

Well, its obviously a EP1 map, so most likely he does not have EP1 installed.
ep1_c17_05.bsp

But the title says HL2

Yes i have it installed.

Try verifying Episode One’s cache.