What causes this error/bug?

[edbeeching]

Hi
Ive been making my second map ever and for some reason objects appear when i compile my map which donnot exist when editing in hammer. Any help with fixing this problem would be great. I have a screeny uploaded but forums wont let me link it cos im new. -.-

[Chamet]

that happened to me last nigh XD, an object just appeard there, like, it was just a texture and you could walk through it.
I had to search for it very carefully on Hammer Editor, it was just a little line with a texture applied to it.
so try zooming in lots and see if you find anything.
However, im not sure if that is exactly what happens to your map.

[Mkz]

hit the unhide button in hammer...