What I want (and have had on my previous PC using the same version of
Outlook) is that each time an email arrives, all my rules are run, and
the mail will match the sender against one of the rules. That rule will
then execute and will play an audio file (e.g. if the mail is from john,
it will play an audio file that speaks "email from john"). I've had this
working in the past, but can't get it going on this new machine.

Each rule is setup like this:

Apply this rule after the message arrives
from Smith, John
and on this machine only
play email_from_john.wav
and stop processing more rules

In my Windows XP control panel, I have sounds setup so that it doesn't
play any audio file on New Mail. I know that would interfere with things.

Right now I have about 6 rules like the one above, and instead of
playing the appropriate wav file, I just get the system default beep
file get played.

If I disable 5 of the rules, so that only the Smith, John one is active,
then it works just fine. If I have more than one of these identical
rules enabled, then I get the system default beep wav instead.

Any ideas ? I'm fairly sure that each individual rule itself is fine,
but if I have them all enabled then somehow I get the default beep.

Config: XP/SP2 with Outlook 2003.