Doug,
The hostIP fix did make it into 4.1.0 and 4.1.1, so that shouldn't be the issue. I did make a change to getHostAddrInfo() in lib/BackupPC/Lib.pm; hopefully that didn't break things.
Can you look in the server LOG files to see if there are any clues while 4.1.1 was running? Similarly, do the per-PC LOG files show anything? Do any of the host directories have a XferLOG.bad.z or XferLOG.bad.z.old file whose timestamp matches the window in which 4.1.1 was running?
If so, please send me the relevant info.
Craig