Were you able to fix your problem. I have a similar issue with a SB Pro not getting an ip from the Router DHCP:
Slingbox broadcastsa DHCP request (DHCP Discover)
DHCP server replies (broadcasts a DHCP offer)
this goes on and on... No DHCP Request after the offer...
I have anotehr SB Pro on same network that gets an IP just fine. I tried only one as well and to inter -chenge the power adapter..
Did you got this solved ?