Hey Wireless,
Have you tried this:
http://www.pocketgear.com/software_detail.asp?id=2867
It may flush any internal network settings cache. I too go between work and home - at work it is static settings, at home DHCP. Haven't had a need to go between two DHCP access points, but I have found that I must pull my WCF12 out everytime I change the network settings to reset it.
From the PocketGear web site:
IP Manager also lets you switch between networks easily. At startup choose between DHCP or a list of static addresses. Each time you enter a new static address, or change your proxy settings, IP Manager gives you the option of adding it to your own database. Just give the new address or proxy setting a description, and it is added to the database. Once you make your choice, reset your Pocket PC and the setting will take effect.
IP Manager allows you to change:
Computer Name
IP address
Subnet Mask
Default Gateway
DNS
WINS
Proxy settings
ActiveSync partner
Use with any standard or wireless ethernet card