SQL & PL/SQL

I'm getting this error some of the type with utl.http requests to certain sources.

ORA-31011: XML parsing failed
ORA-19202: Error occurred in XML processing
LPX-00216: invalid character 31 (0x1F)
Error at line 1
ORA-06512: at "SYS.XMLTYPE", line 272
ORA-06512: at line 81
31011. 00000 - "XML parsing failed"
*Cause: XML parser returned an error while trying to parse the document.
*Action: Check if the document to be parsed is valid.


here's my setup. i'd like to be able to make a change so this goes away, instead of trying to trap it each time, but any suggestions are welcome
SELECT * FROM NLS_DATABASE_PARAMETERS;

PARAMETER VALUE
------------------------------ ----------------------------------------
NLS_LANGUAGE AMERICAN
NLS_TERRITORY AMERICA
NLS_CURRENCY $
NLS_ISO_CURRENCY AMERICA
NLS_NUMERIC_CHARACTERS .,
NLS_CHARACTERSET WE8MSWIN1252
NLS_CALENDAR GREGORIAN
NLS_DATE_FORMAT DD-MON-RR
NLS_DATE_LANGUAGE AMERICAN
NLS_SORT BINARY
NLS_TIME_FORMAT HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZR
NLS_TIMESTAMP_TZ_FORMAT DD-MON-RR HH.MI.SSXFF AM TZR
NLS_DUAL_CURRENCY $
NLS_COMP BINARY
NLS_LENGTH_SEMANTICS BYTE
NLS_NCHAR_CONV_EXCP FALSE
NLS_NCHAR_CHARACTERSET AL16UTF16
NLS_RDBMS_VERSION 11.2.0.1.0