Excahnge 2003 OWA stops responding

We are running a native Win2K3 AD environment with Exchange 2003.  Recently the OWA has been chrashing (once a week for the past month).  There are no errors in the logs and no other trouble except no one can reach the OWA page.   The only change we had was new uses that access their mail through Entourage on Mac's.  
    In trying to fix the web site I've done IIS resets with no effect.  I've tried stopping the website and restarting with no effect.  The easiest solution is a complete reboot, but restarting all the Exchange servives  also fixes the web access problem (for a week).
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msowardsAuthor Commented:
In our case it had to do with drivers for the Broadcom NICs.  They could not handl TCP/IP off loading.  The 'chimney' process would waste handles until we ran out.  We had to turn off TCO/IP off loading.  This corrected the problem.
You are probably running out of ephemeral ports.
type netstat -an
if you are using more (or close to) 5000 connections then that is your problem.
to increase the number of ports available add
MaxUserPort (DWORD) to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
and give it a value of  10000.
You can increase the value up to 65534 but I would increase it gradually until the issue goes away.
I have heard of Mac's causing some problems in the past. If I recall correct Entourage connects through OWA, so would be connected.

Have you run the Exchange Best practises tool on the server? If not then I would suggest that you do so and see if it flags any errors.

Ensure that any AV software is not scanning the Exchange directories as that has been known to cause problems in the past.

msowardsAuthor Commented:
I'm not sure about the ephemeral ports.  Aren't they just a client thing?  I ran the netstat command, but we had just performed a reboot.  Yesterday the entry count was 430+;  today the count is 478.  I'll keep an eye on this.  Also we were scanning the exchange web directory so we've turned that off too.  I'll have to wait a week to see if this error reoccurs.
We are having the same issue. I have been looking for a solution for about a year now, we have to restart the server about once or twice a month.
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