The log entries show:
- 10:51:26] Completed 500000 out of 500000 steps (100 percent)
[10:51:26] Writing final coordinates.
[10:51:26] Past main M.D. loop
[10:51:26] Will end MPI now
[10:52:26]
[10:52:26] Finished Work Unit:
[10:52:26] - Reading up to 3721632 from "work/wudata_00.arc": Read 3721632
[10:52:26] - Reading up to 1774952 from "work/wudata_00.xtc": Read 1774952
[10:52:26] goefile size: 0
[10:52:26] logfile size: 16912
[10:52:26] Leaving Run
[10:52:28] - Writing 5517896 bytes of core data to disk...
[10:52:28] ... Done.
[10:52:29] - Shutting down core
[10:52:29]
[10:52:29] Folding@home Core Shutdown: FINISHED_UNIT
No dice

I also tried restarting the fah6 program.
No dice:

So I uttered a few oaths, and stopped folding on this machine for 48 hours. Then I deleted all the work files and queue.dat, and restarted.
And I have got the same !@# WU again

Estimated time of completion is around midnight CET this evening, but if it just dies again, it will kill off some of my enthusiasm for folding.