Point of Sale Error

[James McDonald <..hidden..>]

When I go to POS => Sale and then click update I get the following error 
in a browser:


 "Internal Server Error

The server encountered an internal error or misconfiguration and was 
unable to complete your request.

Please contact the server administrator, ..hidden.. and inform 
them of the time the error occurred, and anything you might have done 
that may have caused the error.

More information about this error may be available in the server error log.

------------------------------------------------------------------------
Apache/2.2.8 (Ubuntu) mod_ssl/2.2.8 OpenSSL/0.9.8g Server at 
192.168.1.201 Port 80"


I also get the following in /var/log/apache2/error_log

"[Thu Mar 13 08:51:50 2008] [error] [client 192.168.1.7] Premature end 
of script headers: ps.pl, referer: 
http://192.168.1.201/ledgersmb/ps.pl?path=bin/mozilla&action=add&level=POS--Sale&login=jmb1&timeout=3600&sessionid=&js=1&nextsub=openinvoices
[Thu Mar 13 08:58:31 2008] [error] [client 192.168.1.7] Premature end of 
script headers: ps.pl, referer: http://192.168.1.201/ledgersmb/ps.pl";