For some reason, after driving miles along the coast in the 7th episode, I came to a long bridge with a combine fence blocking entrance to it, and the road continues away from the bridge to a tunnel, but that is blocked off also. After killing all the combines in the houses next to the bluff that the bridge is built on, I found the crossbow and a poison zombie on a path leading to a room under the bridge, inside the supports. I believe that this is the correct path to turn off the fence, because although the cable that powers the fence is visible, I can't disconnect it. However, if I try to go through the door, it displays a 'loading' message and then appears to drop me into a dark void, and then kills me and loads my last save before that. I have tried restarting HL2, restarting my computer, and just searching for an hour for a different way forward. Have I been going the wrong way, or is my HL2 bugged (and requiring a reinstall), or is my computer just incompatible with HL2 (it's worked up until now, but just in case I am playing on an HP Envy laptop, running Windows 8).
Note: Sorry that I don't have screenshots, but I am at school currently and I don't have tonight free, so Tuesday I will try to get some up. I was recording my playthrough of HL2, so while I am pretty put off by this problem, I do have video of the entire game up to this point, if it will help. (That won't be available until Tuesday or later either)
Best Answer
Are you referring to this area?
This does sound like a bug. That doesn't normally happen, and the doorway pictured above is the correct path to take.
Verifying the game's files is probably the best course of action. (Step 1, and Step 2 - Select Half-Life 2 instead of Counter-Strike as pictured)
Edit: As noted in the comments below, the poster found that the solution was to restart the chapter.
Images from: http://www.visualwalkthroughs.com/halflife2/highway17/highway17.htm