Has anyone tested Exchange 2003?

I got some problems when I installed
ISAPI filter on windows 2000, it seems that
the Exchange2003 's Logon filter (OWA form logging) not so friend to my filter.

If my filter launched, clients can not login.
(http 500 error).

If clients can login, my filter functions not
work (Notifications I registered never wake up
my filter).

It's very odd, I have to reboot IIS admin or
Information store service even if I removed my
filter.

By the way, I tested Titanium with windows2003 server, very well.

As on windows2003 (IIS6.0) uses different worker processes to contain different filter, it runs
smoothly.

I guess, OWA logon ISAPI dll has some bugs.
Because it share the process (inetinfo.exe) with
my filter.