I'm aware of the fact that it's much more complicated, but suffice it to say the idea of a currency union between northeastern and southwestern Europe was doomed to fail.
Discussion
I hope it will fail and yes it is much much more complicated and a very very VERY long story. But i will try to make it as short as possible. It starts with the fact that markets cannot selfcorrect themselves as Alan Greenspan hoped and there was that crisis with Lehman brothers , AIG not having liquidity (the main problem) etc. Yes the US government intervened and took the money of the taxpayers to correct the market, but still the crisis should be expanded out of the US, in Europe. I am sure you can find plenty of stuff about that, i will only tell that it sounds awful for the $ as a reserve currency to be much softer than the €. So how do you expand the crisis to Europe? Well in Greece there is a candidate (Γιώργος Παπανδρέου) that is also a US citizen, people don't know that he doesn't even speak greek and that he doesn't care about the legacy of his father, only about the citizenship of his mother (that is USA) and, most importantly, european banks, especially german banks, were terribly exposed to greek debt, even though they knew they shouldn't, because it was profitable...
If there are any questions...
I actually knew all that.
Also, that the Germans effectively "lend" the Greeks money at below-market rates, so that they can buy our cars and stuff.
Well if you knew, why voting a guy who, in his ignorrance, wanted to destroy the gernan banks? Maybe you learned that afterwards? Because it was to Greece's benefit (but not to Greece's oligarchs) to default, just like Germany did 3 times in the previous centoury (Greece two times).