LAN DNS resolution has changed - along with lots of other behaviours

Hi

Last Friday I experienced a lot of strange network/firewall behaviour on my Macs, both running 10.6.7. I don't know what the problem is but am trying to isolate it - or them.

Considering just the MacBook Pro, I have been running the same setup for over a year at different locations and never experienced this before. The MBP is named Isola, it runs Windows XP Pro on VMWare Fusion and MAMP as a development/test environment for websites.

Since I have had this setup, with MAMP running and using the normal Apache and MySQL ports I could connect to websites using Mac browsers on: http://localhost/, if I was testing on Windows browsers I would use http://isola/

This worked at home using an Airport connection over a Netgear modem/router:
TCP/IP
Using DHCP with manual address
IPv4: 192.168.0.5
Subnet Mask: 255.255.255.0
Router: 192.168.0.1

Configure IPv6: Automatically
DNS Servers: 192.168.0.1
Search Domains: -

It also worked at the office - 2 Macs networked using a Netgear Gigabit switch, also connected to the building's ethernet system for external internet connection:
TCP/IP
Using DHCP
IPv4: 10.0.21.10
Subnet Mask: 255.255.255.0
Router: 10.0.21.254

Configure IPv6: Automatically
DNS Servers: 10.0.21.254
Search Domains: popcorn

I have two Locations set up in networking preferences, Home and Office. DHCP and DNS at home are provided by my ISP I believe. Apparently the IT infrastructure in the building where my office is located handles the DHCP and DNS.

Since last Friday when I try to connect to http://isola/ using a Windows browser the request either times out (Internet Explorer) or is re-routed to http://www.isola.com (Firefox and some other browsers). In order to the site on my MAMP server I have to use http://isola.local/

I can replicate the same behaviour when trying to connect to the MAMP server using my Mac Pro.

I have flushed both Macs' DNS caches, repaired permissions and tried other stuff which I can't quite remember now. Nothing has made any difference.

I'd really like to know if this new behaviour is likely to be caused by my configuration or the office DNS setup and ideally get it back to what it was before.

Yesterday I started experiencing strange behaviour with the MBP firewall. It may be part of the problem or not - I'll include for information. It has always been on and set up normally - none of the Advanced settings checked. There were a whole load of software listed in the Advanced tab such as Skype, Safari, Opera configured to accept incoming connections. Yesterday for the first time ever I had a whole load of firewall dialogue boxes open on start up asking to allow or block network connections to basic OS X services: AppleFileServer, cups-lpd, cupsd, httpd, krb5kdc, mysqld, nmbd, smbd, vmnet-natd. I think some of these are due to File Sharing and Printer Sharing being enabled in the Sharing Preferences - but they've been enabled for over a year.

Thanks in advance for any advice.