VMWare Fusion Bridged Networking Error

I’m building some simple .NET web services in a VMWare Fusion VM running Windows XP. I’d like to consume those web services from Grails code I’m developing on the host OS, which is a Mac. The easiest way to hit IIS in the VM is to switch the network connection to bridged mode, as shown here:

I had been doing this happily for a week or so, when suddenly yesterday afternoon it quit working. I tried to put a new VM into bridged mode, and I got this unhappy dialog box:

The guest OS (Windows XP) was insisting that the network cable was unplugged on my virtual LAN adaptor, and I had no way to hit my .NET services from the glorious host OS. Googling around a bit suggested that this was a problem when the Mac had more than one network adaptor configured, but that made no sense: I always have two network adaptors (wireless and wired), and have done bridging successfully while using one or the other, and sometimes while both are recognized by the OS as live options for network traffic.

Skipping to the end for your convenience, it turns out the problem was with the VPN. I can use bridged networking as much as I like, just as long as the Mac is not connected to the VPN. Even if I try to establish bridged mode while disconnected from the VPN, then connect to the VPN afterwards, it still disabled by bridged network adaptor in the guest OS. Host VPN and bridged guest simply will not coexist.

Which is great and all, but the .NET services I’m running in XP need to connect to a database server available on the client’s private network, so without a VPN, I’m sunk. The happy ending is that I can establish a VPN connection in the guest OS—in Windows—while the Mac is happily VPN-free. This still disables some of the tooling I rely on for efficient development, but it’s as good as it’s going to get, and ultimately, it’s workable.