******* PLEASE READ THIS AS THIS IS HOW TO FIX YOUR SOLUTION ******
NOTE : you do not have to reset your ps3! only reset your ps3 if the following does not work OR no games will load.
I had the same problem, the ps3 will turn on everything fine, but when i load cod black ops a black screen comes up. but when i load other games such as: Pro Evolution, Cod mw2 it loads fine.
So here is what to do:
1. Delete the 'Game data utility' and 'save data utility' of the game which will not load. (this will delete your for eg if you play cod the campaign mode progress will be lost but your online will be fine.
2. go to GAME SETTINGS under the SETTINGS, Then go to the first one i believe its called, PS UPscaler or something. change this to FULLSCREEN. then go back on the game and it should work, if this doesnt then i think you
should do the playstation restore thing.
IF THIS DOES WORK, then please rate this or whatever you do on here so others can make use of this too.