Since I can't reproduce this problem, would you mind trying to run getent under strace?  It would be helpful to get 2 strace outputs for the same account, one working, one failing.  Call it like this:

  $ strace -o getent-1.trace getent passwd <account>


Thanks,
Corinna

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Corinna Vinschen
Cygwin Maintainer


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Attached.


Thank you