Brushes disappear... frustrating

I've been working on a curved road section for almost a week.

Something that should take 1/2 hour.

I've tried Constructor, 3DWS, and QuArK all in conjunction... here's what happens

Using about 30 cubes or 30 wedges (tried both), I'm creating a 90 degree turn by rotating the pieces.
Obviously, their corners don't line up, so from TOP view ONLY, I move the verts so they line up as best as I can.

Here is where Snap to grid working would help... also a Snap to vert would rock.

Anyway, I get them close... looks good.

Save.... looks good.

File... New.
File... Open the save.

In Wire view many pieces are gone... in ByBrush view, I can see these brushes looking like triangles folded in on themselves.

I delete them, retry and other pieces i didn't even touch since the last save do the same thing (fold on themselves).

I try to open in QuArK, which sometimes shows them as broken, sometimes they look fine inQuark.

I try to open in 3DWS, crash.

I try to open in Hammer... says it won't create any of my brushes because of errors.

Any clues....???
I'm at my wits end and I'm getting pressure to finish this roadway.

Help!