When I have free time in small durations, I often play Free Cell on my phone. The app that I use permits unlimited undos, and because of this I currently have a run of 603 wins, with 655 total wins and 10 total losses.
As is demonstrated by those statistics, my 10 losses occurred during my first 52 games. Prior to using this app, I had only played Free Cell very rarely.
As my statistics approach a 1% loss rate, I have to wonder: Given an unlimited ability to undo your moves, is there any initial deal of Free Cell that is impossible to solve?
A proof one way or another would be ideal (although I admit that I doubt I'd be able to comprehend such a proof), although an authoritative source would be a good alternative.