I read this one on another site.

The theory is that we have been experiencing the series from the point of view of Amy/Rory, and that they have not been meeting the Doctor in the right order. The idea is that we, the viewers, have been experiencing the past two seasons the same way the Doctor experiences River -- everything is out of whack.

In this theory, when the Doctor was poisoned in Let's Kill Hitler he didn't use his 32 minutes to change into a tuxedo. Instead he travelled back to the very start of the sequence, to The Eleventh Hour, and that the wonkiness the Doctor was feeling at that time was a result of the poison. The Doctor walked into a tree and later was seen stumbling and clutching his stomach. This is a compelling notion. I don't think it's correct, but I do think it's cool. I don't really know how it would all tie together.

That Doctor who went back to meet young Amelia and then skipped ahead 12 years, at that point went back into another time, and then it was a younger version of the Doctor who showed up outside her home on the eve of her wedding date, two years later, somehow alterted that he should do so to take her out of that time because of what was going to happen on that wedding date (the destruction of the TARDIS). In that case, the Doctor would have known more about her than he let on. That younger Doctor went through the rest of the season with her in order.

Meanwhile, in Let's Kill Hitler, the tuxedo Doctor who showed up was not poisoned. Either he was faking it to take River's regenerations away or he was afflicted by something else. He was wearing the tuxedo because he had just come from the season 6 finale, The Wedding of River Song.

This theory turns the entire two seasons into what's known as a bootstrap paradox, where things happen later because of what happened earlier, but the things that happened earlier only happened because of what happens later, and all the timelines are jumbled up. Every time the Doctor was separated from Amy/Rory by any length of time would be a chance for a Doctor in a different part of his timestream to show up.

The theory continues by suggesting that time itself is going wonky. In Closing Time, there's a newspaper he shows Craig, dated April 19, 2011, three days before his death. There are two stories you can see on the paper about someone going to the Olympics and something else. When the Doctor shows up in the cornfield in Let's Kill Hitler, he has an old newspaper in his hands, presumably from Leadworth, far from the scene of Closing Time, and at a different time of year (there's corn in the fields). The same two stories are on the paper. Production error? Maybe. The theory suggests that this is an indication of time collapsing and going all wrong. The theory believes that the Silence have set this in motion by making River kill the Doctor. According to the theory, the Doctor's death is indeed a fixed point in time, but it's not supposed to happen for a long time yet. The Silence used their knowledge to disrupt the timestream by setting up the Doctor's death, breaking the fixed point in time and sending everything into a downward spiral. The Doctor, at some point aware of what was happening, invited versions of Amy, Rory, and River to his death in order to set up a time loop that completes right before the break point of his death occurs, so that every time it loops around things will go slightly differently, with younger Amy/Rory meeting up with younger Doctor and giving him the warning this time, a warning he didn't have the first time around. This gives his younger self a chance to fix it before the death occurs again, fixing time before it completely unravels.

I don't know how likely any of this is, but I actually sort of like the idea of the Doctor's appearances coming in the wrong order. It might work on some level to help explain the different ties and the other odd things that creep in about him sometimes. As River says in Let's Kill Hitler, "Watch out that bow tie!"

I love mad theories like this even if I don't believe in them. It's impressive how the various red herrings and clues strewn throughout the series can be woven together in different ways to provide all sorts of explanations. And then if last season is any indication, Moffat will do something completely different that no one predicted, but which still fits all the clues.