No I don't have a leak, I've alt P'd and nothing came up apart from something about player starts, which I do have anyway..
One thing that does happen however is when I'm compiling something comes up and says 'Vrad.exe' isn't responding, is that a problem? It still carries on with the compile and stuff and runs the map so I don't know what it's all about!
What you're describing sounds exactly like a leak, and I don't think leaks show up with Alt P. Do a quick compile (check 'none' for VIS and RAD and 'fast' for BSP, check 'don't run game after compiling'), then copy the compile log into the
interlopers log checker.
If it turns out that you have a leak, open the 'map' dropdown menu in Hammer and select 'load pointfile'. A red line will appear in your map, and by following it you should hopefully be able to find the leak.
EDIT: Ninja'd. Oh well. Here's a bonus tip. Since func_details and displacements don't seal despite looking solid, unchecking those in the visibility-list thing on the right side of the screen may make leaks easier to locate.
Bonus bonus tip: don't feel dumb for not knowing this stuff. It's really unintuitive. I mean, if one's water entity is invisible, it's logical to assume that there's something wrong with the water rather than the outer walls of the map.
Come to think of it, has anyone made a tutorial explaining all those little confusing things all newbies encounter? 'Why is there a purple checkerboard on my control point', 'I textured my walls with a pretty sky texture with clouds and stuff, why doesn't it look good in-game?' and so on.
