What is the term for when too many choices results in inability to decide?
It is "paradox of choice". See these resources:


The paradox of choice: why more is less By Barry Schwartz (Google Books)
Excerpts from the above book by Barry Schwartz (.doc format)
Positive Psychology in Practice chapter 6 Doing Better but Feeling Worse:
The Paradox of Choice by Barry Schwartz and Andrew Ward (.pdf format)


I actually haven't been able to find anything in my search just now, but I remember some claims about a year ago that recent experiments had suggested that the original results were somewhat over-blown.