Hylafax 6.0 No response to PPS repeated 3 times Ubuntu Jaunty.

I recently upgraded from a 4.x version of Hylafax to the latest binary
available for Ubuntu.

I'm using this command to send multiple faxes to multiple machines:

sendfax -m -n -d FaxRecipient@FAXNUMBER /pcshare/faxes/pdfs/*.pdf

After sending about 200 faxes, one in eight faxes fails with the following
error in the log:

No response to PPS repeated 3 times.

Usually the fax recipient states that the first of two pages was properly
received, but the second wasn't received.

When trying again with only one page, the log shows the same message: No
response to PPS repeated 3 times.

It appears that the remote fax machine isn't responding to the PPS signal at
all, whether EOP or MPS type.