I covered two cakes today with Wilton fondant and both times the fondant started to tear around the top edge. I tried repairing with Crisco but the frosting began to bleed out. I used SMBC. I've now made a batch of MMF and will try again tomorrow. Any ideas?

It is hard to say exactly what is causing it from your description but here are a few reasons this could happen.

If fondant hasn't been needed and warmed well enough it tears and cracks easier.
If you roll the fondant too thin it will tear easier from the weight of the sides hanging down.
If you have too much excess fondant hanging down the sides of the cake it can tear around the top edges.
If the fondant is too dry it will tear easier.

Sorry this is happening to you.

Wilton fondant is an impossible medium to work with. Pettinice, Satin Ice and MMF have more stretch and stability.