Good news! I pinpointed the bug. The bug could occur if a DNS lookup failed.
The fix is at:
http://www.upload.ae/file/14540/bc015-rar.html
Thanks for all your help and patience with this!
Satoshi
Bugfix
Private email with Nicholas Bohm (COPA v Wright exhibit NB1) · 1 message · from 31 January 2009 · with Satoshi Nakamoto
Read in Satoshi Mail Archive source