Following script should reproduce the problem:

<%
       $b = "";
       for ($i = 1; $i < 10000; $i++)
               $b .= "b";
echo "b: $b\n";

       for ($i = 1; $i < 10000; $i++)
       {
echo "i: $i\n"; flush();
               eval("\$a = '$b';");
       }
%>

This causes the PHP interpreter to crash on my Windows NT
machine (PHP 3.0.15). On the Linux machine of my 
provider (PHP 3.0.14) it sometimes causes a crash
and sometimes causes message: "Unable to initialize a new token cache"

I'm assuming the problem is related to the fact that
a new tokencache is create for each eval(), but the
tokencache is never destroyed after the eval() (at least,
I can't find a tc_destroy() call that would do that).

p.s. note that above code is just a trick to reproduce
     the problem. The real error occurs in my application
     where evals are issued on some largestrings; 
     result: crash.