"Ran Out Of Memory" Error, ASP 0107

I have a problem with a home-made DLL used in an ASP environment. It
is coded in VB6, apartment-threaded.

The DLL returns a binary PNG stream (an image). I use it with ASP's
Response.BinaryWrite to display a dynamic image on a web page.

The server is Windows 2000 SP4.

The web page contains anywhere from 1 to 6 images, where the HTML code
is something like "<IMG SRC='img.asp?some_parameters...'>". Also, the
web page contains a timer so that these images are refreshed every 10
seconds. This means that the "img.asp" page, which is instantiating
the DLL, can be called very often.

When I start IIS, everything is fine. Then, after about 4-5 minutes,
the img.asp page starts to return the 500 HTTP error code, with the
mention that "Server.CreateObject failed : ran out of memory". The
internal error code is "ASP 0107". Sometimes I also get the "Type
mismatch - ASP 0105" error.

The IIS application is set up as highly isolated.

I tried de-registering and re-registering the DLL, but that didn't
help.

We have another server (more recent) set up the same way, except that
it's SP3, and it works just fine. Note that before setting the
application as highly isolated in IIS for that second server, we were
having the same problems.

I have searched extensively on the Microsoft web site as well as
Google Groups. I found quite a few references to the "ran out of
memory" error, but couldn't find a solution that would correct my
problem.