AV could be a problem for every conference. Many times I've found myself with a broken projector before learning you always need a plan B.
Springwise points out Meeting Tomorrow as a good solution, if not the way to go. The idea is pretty simple but with a huge gap in the market, renting AV.
Hotels and conference venues will charge a damn fortune to rent cheap AV material and most of the times they will not committ on the reliability of the equipment.
The good things of this service are that there is same day delivery and that they propose to rent alternative AV, should the projector stop working.
Now that sounds like a good insurance to me. Have a look.