Attempt to make praline paste failed -- what should I do differently?
Upon reading those instructions, I can picture vividly the scenario you describe. It seems like the caramelized sugar would of course solidify and cleave to the bottom of the (relatively cold) food processor as you pour it in. Or is the friction of the food processor supposed to keep the caramel melted at its original temperature as it whirls around while the nuts pulverize? That even sounds kind of unsafe somehow.

Curious, I looked up other recipes for praline paste on the internet - and there are lots. These are the first 4 I came across:

http://joepastry.com/2011/making-praline-paste/

http://www.thedomesticfront.com/pralinepaste/

https://beammeupbiscotti.wordpress.com/2012/04/14/useful-tips-how-to-make-praline-paste/

http://www.chefrachida.com/homemade-hazelnut-praline-paste/

All of these specify letting the caramel and nut mixture harden and cool on a non-stick surface first, and then you break it up into pieces and put into the food processor. The first reference shows pictures of the progression of the product from chunks to powder to paste as the food processor works. 

Even though it is contrary to the recipe, perhaps it would work better if you cooled the mixture before processing. I wonder if some sentence or phrase about the pre-processor cooling step got accidentally left out of your recipe.