So I was working on my map and messed with a brush to change its vertex and make it a triangle shaped brush and then copy and pasted it twice. While I was making this vertex adjustment Hammer asked me if I would like to combine the vertices that had met and for whatever reason I said no. It hasn't been a problem in the past so I didn't think much of it. Lots of work into the map later, I tried to compile the map for testing and I got the error:

Brush 8392: FloatPlane: bad normal
Side 3
Texture: METAL/BLACK_FLOOR_METAL_004B

and then Hammer crashed.

I didn't think it was a big deal so I checked out the VDC to look up the compile error and saw that it had to do with merging vertices or something so I figured it would be an easy fix. I loaded Hammer back up to it asking me if I wanted to re-open the crashed map. I said yes and then another error came up talking about there being 3 bad objects in the map and suggested I re-save a version in which the objects had been automatically deleted. Sounded like a good idea so I accepted only to see yet another error saying "error 1: no permission" and then Hammer would crash again. I tried a few more times to the same errors and now any time I try to load up my map Hammer just crashes with no warning or errors. At this point, I'm just trying to figure out if there's a way to recover my map's previous saves. Can I just open the last map I compiled and edit from there? Is there a solution to this? It would save me some time to not have to re-make an entire room.

Assuming you did not disable it, Hammer autosaves your map occasionally to (by default) C:\HammerAutosave. You can try looking in there and seeing if the autosave version of your map works.

Generally you shouldn't vertex edit unless you really know what you're doing. And even then it's not the best idea. If Hammer asks you if you want to merge vertecies then odds are, again, you always want to hit Yes unless you really know what it's doing.

You cannot edit a compiled BSP. Absolute worst (and I mean worst) case scenario, you could decompile your map to get your work back. But your map is going to be trashed to hell and back, it won't be pretty.

Also when you compile, the compiler saves yet another backup of the .vmx file. This is an at-compile time copy of your .vmf file. Assuming you did not compile between the last successful compile of your map and when you got the error, you could try renaming that back to .vmf and see if that works as well.

Well, apparently the Portal 2 SDK doesn't have the AutoSave feature enabled by default as I was only able to find maps I made on the Source SDK for Portal 1. Also, for future reference, what do you suggest as an alternative to vertex editing? I'd also like to note that I wasn't doing anything ridiculous with the Vertex tool. Just a simple slant to both sides of a square.

EDIT:
Valve recognized the problem and it's somewhat common apparently. Here's the post from the Steam forums:

Quote:
We've got a fix in the queue to resolve this problem. The issue was that there was an invalid brush in the map and Hammer was attempting to fix this on reload. Two problems could arise at that point: it could crash Hammer or you'd get a permission denied message. Both these issues will be resolved in the next update.

That's good news then. I'd hold on to your VMF until the next update, which I would take a guess would be on Monday. If you are feeling really ballsy, you can manually edit your VMF file. They are nothing more than plain text files. Open it up and see if you can find that brush number, and delete the section for it, then try opening it again. Obviously you want to keep a backup copy of the original first since you could totally fuck up the map doing this.

As for making the ramp, if you are doing something that simple then I would really suggest using the Clip tool over the Vertex tool.