Internet fails every 5 hours

I am in urgent need of some assistance.  My client has a windows SBS2003 server running Exchange 2003.  We use a sonicwall Pro for router/firewall/vpn.  My client's office had renovations done to it during June and July and I hosted the server and sonicwall on my Verizon FIOS.  For two months, it worked perfectly without any problems.  I have recently brought back the server and sonicwall to the client office location and connected everything back the way it was and modified the settings on the sonicwall for their Verizon FIOS.  

Everything will work perfectly for about 5 hours.  Server, Internet, Incoming and outgoing emails are perfect.  But it seems like every 5 hours, the Internet goes down which prevents me from supporting the network remotely.  All PCs and server lose access to the internet so emails stop working as well.  A simple reboot of the sonicwall restores everything perfectly, but only for another 5 hours, but then it goes down again.  I am going nuts trying to figure this out.  I don't think it is the server because rebooting the sonicwall gets everything back up so I am under the impression that this is sonicwall, or FIOS related.  

I have checked all my settings so many times.  DNS, Firewall, DHCP, it all looks good.  What could cause it to work for 5 hours and then cause an internet outage?

Any suggestions?
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There could be a hardware issue with the Sonicwall. Also check release notes for current firmware releases and possible bugs.
Double-check physical connections.... it could be something simple like a Speed/Duplex mismatch with ports.  Ensure all ethernet ports are set to Auto/Auto (Speed/Duplex). Don't mix and match with 100Mbps/Full. I've seen this cause networks to fail.

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agree with the speed/duplex.  you might confirm the MTU is set right as well.  check out my article., is it a statically assigned public IP or DHCP?
I feel that this issue was introduced after you changed the settings of the Sonicwall.  However, it is possible that during the renovations something was damaged (cable).  Make sure Sonicwall is runing latest firmware and then reset to factory defaults and reconfigure if possible.  Another troubleshooting step would to place another router in (doesn't have to be Sonicwall) and see if that drops every 5 hours.
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check Firewall setting , may be big log files or too many request on single port can cause firewall to hang, check log 1st

Is power supply of the SonicWall working properly?!
It seems like a hardware problme
Check the situation with the processor load of the sonicwall. It might get overloaded for some reason.
@PCNNY :: It'd be super to get some feedback from you at this point.
PCNNYAuthor Commented:
sorry for the delay.  This issue has still not been solved.  I am conviced it has to be a conflict of rules on the sonicwall, but I am at my wits end on this.  I have no idea what the issue is or even where to look.  
i don't see any feedback regarding my suggestion here regarding the MTU:

PCNNYAuthor Commented:
I was told several times that the MTU is not the reason this is happening.  I was told during a recent call that this is a known issue with FIOS on sonicwalls and they have a new firmware which I am goign to install tomorrow.  I will keep this thread posted of the outcome.  Thank you.
that's great....can't wait to hear how it goes!
PCNNYAuthor Commented:
The new firmware was applied today and since then the FIOS has remained active.  I will be monitoring this all day tomorrow, but it is safe to say that if it goes the whole day without any interruptions, the issue is resolved.  I will keep you all posted and thank you so much for your helpful suggestions.
that's awesome!  glad to hear the firmware update fixed it.
digitapCommented:'s nice of you to share the points with me!
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