I've setup Hammer v3.4 using the standard HalfLife.fgd file and ensuring that the Build tools are Zoners build tools. A typical BSP file that has worked for me is to create a single cube and hollowed out at 50 units. Place a single Entity with normal light properties into the center of the cube, no flickering etc. Ensure that you place the cube at the center of the BSP world grid in Hammer. If you place textures onto the walls, use the Wally Texture extractor utility to ensure that all textures from the WAD files are in the same directory has the BSP file and your DBPro project. Get the Wally tool from http://prime.telefragged.com/wally
I've noticed that people who load BSP files forget to use the command SET BSP CAMERA <camwra number>, causing nothing to be displayed. Do these things and get back to me, hope this is useful in some respect.
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