Correct me if I'm wrong, since I only got my information from non-academic sources, but if I recall correctly the problem was that with the inflation, you would have to apply both the theory of general relativity (the science of the really big), and quantum theory (the science of the really small). In which case they totally don't work together and you would get really weird numbers.
Would a more logical explanation not be that our current theories are likely to be flawed, just like Newton's theory about gravity was flawed (but nevertheless incredibly useful) ?
More at its core is that it means that the expansion exceeded the cosmic speed limit, the speed of light. Two of the competing theories have been a rapid expansion (inflation) and another that two branes collided and the big bang started in an expanded state. As of late, it appears there has been more confirmation of the former rather than the latter. From what I've read, it is as another commenter noted -- the universe in it's earliest state did not yet conform to the rules of physics as we know them today. This early state is something on the order of the first trillionth of a trillionth of a trillionth of a second.
Would a more logical explanation not be that our current theories are likely to be flawed, just like Newton's theory about gravity was flawed (but nevertheless incredibly useful) ?