Well, if this was my problem, which I'm glad it isn't, here is what I would do.
Duplicate the sequence and remove all the effects.
Try to export the first clip. If that works, try to export the first two clips.
If that works, tries to export the first 4 clips. Keep doubling up until you get to the end.
If all that works, do the same thing with all your effects. This should pinpoint your problem.
If the first clip (without effects) doesn't work, try another clip or a clip of another format to try to isolate your problem. If that doesn't work, you have a system problem.
Basically, you have to eliminate possibe problems.
Please let us know how you make out.