[Users] get_hdr_field: bad to header...

Hello, We have a few hundred users registered to a openser we are running and everything works fine, however i get som error messages in the logs I would like to get rid of... //sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: ERROR:parse_from_header: bad from header /sbin/openser[28867]: xl_get_from: ERROR cannot parse FROM header /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: xl_get_to: ERROR cannot parse TO header /sbin/openser[28867]: [REGISTER] from [<null>] to [<null>] /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: ERROR:maxfwd:is_maxfwd_present : parsing MAX_FORWARD header failed! /sbin/openser[28867]: ERROR:parse_from_header: bad from header /sbin/openser[28867]: insert_RR(): From parsing failed /sbin/openser[28867]: record_route(): Error while inserting Record-Route line /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: find_first_route: Error while parsing headers /sbin/openser[28867]: analyzing REGISTER request /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: find_credentials(): Error while parsing headers /sbin/openser[28867]: pre_auth(): Error while looking for credentials /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: ERROR: get_hdr_field: bad to header /sbin/openser[28867]: ERROR: bad header field /sbin/openser[28867]: ERROR: build_res_buf_from_sip_req: alas, parse_headers failed /sbin/openser[28867]: pre_auth(): Error while sending 400 reply / Anyone has a clue what I can do to debug this to find out where the request are coming from or what can be done to stop the invalid(?) requests from being processed and clutter my logs? Thanks Lars Sundqvist