[FX.php List] FileMaker Error 958

[Someone]

Hi,
I'm getting an this 958 error occasionally during FMNew and FMEdit  
actions , therefore it was hard to duplicate.
It's running on a Windows 2003 Server box and FMSA is on the same box.
The site is secure (https) and in 3 languages.

There are some validations but nothing that should create an error.  
Paragraph returns validations for fields, where data comes from <  
input type=text>.
I created a new record with the same info in filemaker to see if any  
validation alert happened, but nothing.

I used define("DEBUG", true); and here's  the URLs.

Accessing FileMaker Pro 7 data.Using FileMaker URL: http:// 
XXX:XXXXXXXX at XX.XX.XX.XX/fmi/xml/FMPXMLRESULT.xml?-db=AWID.fp7&- 
lay=web_org&-max=50&organization_name=Solidarit%E9+des+PayXXXX+des 
+Orangers&org_phone=&-new

Accessing FileMaker Pro 7 data.Using FileMaker URL: http:// 
XXX:XXXXXXXX at XX.XX.XX.XX/fmi/xml/FMPXMLRESULT.xml?-db=AWID.fp7&- 
lay=web_contacts&-max=50&orgID_nbr=&name_first=Marie 
+GermXXX&name_last=O.+JN-XXXXXXX&salutation=Mme&position=Pr% 
E9sidente&home_address1=6%2C+Impasse+Gabriel%2C+Rue+Fernand%2C+Canap% 
E9+Vert&home_city=Port-au- 
Prince&home_prov_state=&home_pc_zip=&home_country=Haiti&home_phone=&home 
_fax=&email_primary=spohaiti% 
40hotmail.com&language_correspondence=English&language_primary=&age_rang 
e=26+- 
+35&enLACes=Yes&Carrefour=yes&resourceNet=Yes&password=XXXXXXXX&mail_pre 
ferred=Home&member_status=Individual 
+Member&category_member=Low&category_institutional=Low&income=under+US 
+%2410%2C000+per+year&age_range=26+-+35&date_memStart=06%2F11% 
2F2005&date_memExpiry=06%2F10% 
2F2006&value_statment_ind=Yes&name_preferred=1&-new

Thanks for the help
Frank