Sonicwall One-to-One NAT problem

My client has a Sonicwall TZ 180 Wireless running Standard OS.  They wanted to host their own website, so I setup the web server with a static IP.  I then configured One-to-One NAT on the Sonicwall, using the 2nd of two IP addresses provided by Cox.  All worked beautifully and has been working for 3 months.
Last night, one of the employees went into the office when they realized the web server was not available and found the web server apparently installed some updates and restarted itself.  It was configured for DHCP and no longer had a static IP.  He configured it for the same static IP.
I can remote into the web server.
I can remote into the SBS server and access the website by entering http://webserver.
I cannot browse the Internet from the web server.
If I ping www.google.com from the web server, it resolves to the correct IP, but I receive request timed out messages.
I found that if I disable One-to-Onet NAT on the Sonicwall, I can browse the Internet from the web server.  

As far as I am aware, nothing on the Sonicwall changed.  I don't believe anyone had the password to make any changes.  The web server restarted and was configured with DHCP, so obviously there were some definite changes there.  Disabling One-to-One NAT and being able to browse from the web server and being able to access the website from the LAN certainly make it appear as if the Sonicwall is blocking (or not properly routing) HTTP traffic to the web server.

Does anyone have any suggestions on how to go about troubleshooting this issue?