Passing special characters in query string

Hi

I occasionally pass error messages to an asp.net page via the query string via a vb .net program.

Sometimes the error messages dont get through due to certain characters in the query string.

How could i pass these special characters across without messing up the query string (eg an error message containing an '&')

or

If anyone has a better way to pass data to an ASP .net page please tell.

Thanks
Adam