I think this has been addressed from all angels but let me expand on one. If it works with DHCP but doesn't work with static IP addresses then I would check the following:

1. Make sure the Default route is the same as used in DHCP
2. Make sure that any static routes are applied
3. Make sure that your primary and secondary DNS are correct
4. Make sure that the workgroup is the same (if applicable)
5. Ensure your netmask is correct
6. Finally make sure that the IP addresses you are assigning fall in the subnet that the router directs, but are not used by other machines.

If it worked with DHCP there shouldn't be a reason it doesn't work with static IP addresses if all of this is correct. Well no reason I can think of.