Losing network when machines switched off

I have two desktops running Win XP connected together via a D-Link 5 port hub with a HP 4050N printer connected to the hub also. I also have a cable modem connected to another ethernet card. I've had this setup working for >18 months but in the last month (just before I installed the cable modem) every time I switch off the machines, the next time I boot them up the network doesn't recognise anything. in fact I have to run the network wizard to set every thing up again including connectivity between both machines, the printer and ICS. The modem was initially connected via a USB port but I changed this to a ethernet card thinking this may be the problem but to no avail. After running the wizard everything works fine as long as the machines are left on.
All cards are automatically assigning IP addresses. Would setting static IP addresses help? Which cards would need static addresses? I presume the client machine would. On the host machine I presume that the card connecting it to the hub would be the one to set up a static address on but am unsure.
Would appreciate advice.