Validation of recursive function call fails

Question

We want to use a call to a recursive function from a HTMLDB application. It should be used in a page region to generate a query string ("PL/SQL function body returning SQL query"). Everything works fine with a call to a non-recursive function. The recursive function also works fine when called from SQL+.
After pressing "Apply changes" on "HTML DB Home>Builder - Application 148>Page Definition>Edit Page Region"-page I get the following error message after a long delay:
Function returning SQL query: Query cannot be parsed within the Builder. If you believe your query is syntactically correct, check the ''generic columns'' checkbox below the region source to proceed without parsing
(ORA-00600: internal error code, arguments: [kohdtf048], [], [], [], [], [], [], [])
I assume that the validation routine follows the recursion until the memory limit is reached.
Please give me a hint how to solve this problem.
DB version: 10.1.0.2.0
HTMLDB version: 1.5.0.00.33
running on Win2000 server

Answer 1

Since the original function is confidential, I have created a simple one showing the same behavior (and the same error). Termination does not depend on session state:
Called function (to replace spaces with #):
create or replace function MF_Test
     p_querystring     varchar2     
     return varchar2 is
     v_position integer;
begin
     v_position:=instr(p_querystring,' ');
     if v_position=0 then     /* termination condition */
          return p_querystring;
     else
          return substr(p_querystring,1,v_position-1)||'#'||MF_Test(substr(p_querystring,v_position+1));
     end if;
end MF_Test;
calling function (from the page region, to generate a query string):
declare
q varchar2(500);
begin
q:='select * from hardware where model=''';
q:=q||mf_test(:P3_SEARCH);
q:=q||'''';
end
Validation seems not to terminate in case of recursive function calls.
Thanks for your input.