sp_preprexec error

Hello,

I am receiving the following error when sending a paramaterized statement
from a web page to SQL Server via ODBC connection

Msg 8179, Level 16, State 2, Procedure sp_prepexec, Line 1
Could not find prepared statement with handle 1.


Here is the captured statements received by SQL server (captured by Profiler):

declare @p1 int
set @p1=1
exec sp_prepexec @p1 output,N'@P1 nvarchar(5)',N'SELECT userid
FROM usertable
WHERE username = @P1
',N'admin'
select @p1

The odd thing is, if I copy and paste into Query Anylzer, and comment out
line 2 (set @p1=1), it works fine.....uncomment line 2 and I get the same
error.

Can anyone tell me the cause of this and a possible work around? I don't
know how to tell the CGI script on the web page not set a value of @p1 (not
sure it is even responsible for doing it).

Thanks,
Mark