OWA not opening for users

Running Exchange 2007 SP2 on 2003 R2 Enterprise SP2

Users go to our internal homepage and click on webmail link to access OWA.  Page that pops up says IE cannot display this page.  If user hits refresh enough times it will eventually come up.  This started Tuesday morning but no changes were made to Exchange or any pc's Monday night.  There are also no errors on Exchange box.
Also, sometimes when users try to reply to an email, the email box pops up blank.

It is happening with both Vista and win7, both 32-bit, but IE version ranges from 8 to 10.
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Delphineous SilverwingGood Ol' GeekCommented:
Can you repeat this issue when running OWA local on the server?

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meAuthor Commented:
Does not seem to happen on the server.  Tried it several times and it loads fines
Delphineous SilverwingGood Ol' GeekCommented:
Managed network switch? Check for errors on the port and ensure the duplex and speed are correct.

Double-check the network settings on the server, make sure gateway, mask, etc didn't get changed when you weren't looking.

Have you rebooted lately?
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meAuthor Commented:
All settings are correct and rebooted Tuesday night hoping that would resolve the issue, but it didn't.  Will have a look at ports and get back
meAuthor Commented:
There are no errors on the ports and all setting on the ports are correct
Delphineous SilverwingGood Ol' GeekCommented:
Is this also your mailbox server - any issues with Outlook remaining connected?
meAuthor Commented:
Yes, this is also the mailbox server.  Outlook has had no issues.
Delphineous SilverwingGood Ol' GeekCommented:
Are you forcing SSL?  If not, does the same behavior happen if not using SSL?

I'm thinking this is performance related. How do the CPU cycles look? It's an Exchange server so we know memory use is nearly maxed.
meAuthor Commented:
Not forcing SSL.  CPU is hanging around 2-5% and have seen it spike all the way up to 7% once ;) and you are correct about the memory.  Looked at network activity and it looks fine, no spikes there either
dhsindyRetired considering supplemental income.Commented:
From input so far, I think I would start looking for hardware errors - storage I/O errors, memory errors, etc. Have there been any automatic software updates that you might not be aware happened?
meAuthor Commented:
No software updates have been pushed to the server and I know this as I push all updates.  I will check hardware for any errors and let you know.
meAuthor Commented:
Problem solved!!  Web filter had been disabled when a new firewall was installed, not my doing.  Over the weekend the web filter was enabled again and now OWA is working great.  Not sure why that is the case, but hey, it's working now.  Anybody know why?

Your time and efforts, even tho they appear to be in vain, will be rewarded.  I appreciate the help on this problem
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