I've been wirting software for more than 20 years and have dealt with some random number generator algorithms. I was working on one for a statistical analysis program and found out truly difficult it is to write one. What I discovered is that depending on how the generator is "seeded" (be it system time, etc.) they will have a tendancy to favor certain numbers or sequences.
I notice that while I played on Pokerstars
they seemed to flop Aces constantly while at Noble it's middle cards. I agree that no company will risk rigging the games; however, the random number generator used in their software may make things happen more often.
Perhaps hi chip stack is used as the seed in some software...?