Lost prints ReadClient() 5 IPP Read Error!

[Jez]

We are experiencing intermittent lost prints using cups 1.1.19 on RedHat 
6.2 (built from source). We use system V style interface scripts written 
in perl.

Requests are sent from the local machine, not from the network. The 
printers are NT4 shares


The problem seems to occur if prints are sent in rapid succession:

 From the access.log:

localhost - - [17/Feb/2005:10:29:44 +0000] "POST / HTTP/1.1" 200 140
localhost - - [17/Feb/2005:10:29:44 +0000] "POST / HTTP/1.1" 200 140
localhost - - [17/Feb/2005:10:29:44 +0000] "POST / HTTP/1.1" 200 80
localhost - - [17/Feb/2005:10:29:44 +0000] "POST /printers/printer5 
HTTP/1.1" 200 10974
localhost - - [17/Feb/2005:10:29:45 +0000] "POST / HTTP/1.1" 200 140
localhost - - [17/Feb/2005:10:29:45 +0000] "POST / HTTP/1.1" 200 140
localhost - - [17/Feb/2005:10:29:45 +0000] "POST / HTTP/1.1" 200 80
localhost - - [17/Feb/2005:10:29:45 +0000] "POST /printers/printer5 
HTTP/1.1" 400 0

 From the error_log with log level DEBUG

D [17/Feb/2005:10:29:45 +0000] AcceptClient() 5 from localhost:631.
D [17/Feb/2005:10:29:45 +0000] ReadClient() 5 POST / HTTP/1.1
D [17/Feb/2005:10:29:45 +0000] ProcessIPPRequest: 5 status_code=1
D [17/Feb/2005:10:29:45 +0000] CloseClient() 5
D [17/Feb/2005:10:29:45 +0000] AcceptClient() 5 from localhost:631.
D [17/Feb/2005:10:29:45 +0000] ReadClient() 5 POST / HTTP/1.1
D [17/Feb/2005:10:29:45 +0000] ProcessIPPRequest: 5 status_code=1
D [17/Feb/2005:10:29:45 +0000] CloseClient() 5
D [17/Feb/2005:10:29:45 +0000] AcceptClient() 5 from localhost:631.
D [17/Feb/2005:10:29:45 +0000] ReadClient() 5 POST / HTTP/1.1
D [17/Feb/2005:10:29:45 +0000] ProcessIPPRequest: 5 status_code=0
D [17/Feb/2005:10:29:45 +0000] ReadClient() 5 POST /printers/printer5 
HTTP/1.1
E [17/Feb/2005:10:29:45 +0000] ReadClient() 5 IPP Read Error!
D [17/Feb/2005:10:29:45 +0000] SendError() 5 code=400
D [17/Feb/2005:10:29:45 +0000] UpdateJob: job 92288, file 0 is complete.
D [17/Feb/2005:10:29:45 +0000] CancelJob: id = 92288


Can anybody shed any light on this?