Intermittent Missing seperator in POST line

Hi, 

I'm using dwr version 1.1.4, on tomcat 5.1.7 with mod_ajp_proxy and apache.  js, css etc is being served out by apache, and tomcat is handling just the servlets and jsp.

Occasionally I get an error similar to the following:

Feb 26, 2007 4:14:17 PM uk.ltd.getahead.dwr.util.CommonsLoggingOutput warn
WARNING: Missing separator in POST line: ^@^HHTTP/1.1^@^@*/dwr//exec/CartManager.getPropertyName.dwr^@^@^N205.206.21.168^@��^@^Owww.pizza73.com^@^A�^A^@^LC*/*^@�^G^@
Feb 26, 2007 4:14:17 PM uk.ltd.getahead.dwr.util.CommonsLoggingOutput warn
WARNING: Missing separator in POST line: text/plain^@�
Feb 26, 2007 4:14:17 PM uk.ltd.getahead.dwr.util.CommonsLoggingOutput warn
WARNING: Missing separator in POST line: ^@+https://www.pizza73.com/order/checkout.html^@�^D^@^Een-
us^@�^C^@
Feb 26, 2007 4:14:17 PM uk.ltd.getahead.dwr.util.CommonsLoggingOutput warn
WARNING: Missing separator in POST line: gzip, deflate^@�^N^@AMozilla/4.0 (comtible; MSIE 6.0; Windows NT 5.1; SV1; (R1 1.5))^@�^K^@^Owww.pizza73.com^@�^H168^@�^F^@
Feb 26, 2007 4:14:17 PM uk.ltd.getahead.dwr.util.CommonsLoggingOutput warn
WARNING: Missing separator in POST line: Keep-Alive^@^@
Feb 26, 2007 4:14:17 PM uk.ltd.getahead.dwr.util.CommonsLoggingOutput info
INFO: Exec[0]: 
CartManager.options()

It often coincides with the following error message:
2007-02-26 16:14:17,644 [TP-Processor14] INFO  org.apache.jk.common.HandlerRequest - Unknown message 0

Any ideas to what's going on here?  

Thanks,

Chris.