it's a known problem with the game, not sure why it's happening online, please check your internet connection first.
Nintendo used to have a policy of paying to ship your wii for new "disc-reading-lazer-stuff" just for buying the game meaning Black Ops is notorious for eating disc drives. HOWEVER that policy has expired BUT you may still qualify for a shipment out of a wii system warranty. I suggest contacting nintendo costumer service either through telephone (1-800-255-3700) or go to http://www.nintendo.com/consumer/index.jsp and let them know- they heard it 1,000,000 times before. can't promise anything after that. good luck!