It is way more complicated that that but basically it's the various eurozone government (just like many other governments) who did mismanages since decades and now the house of cards is starting to fall.
Here's an oversimplification: basically by running always on deficit the various eurozone countries have reached closed to an unsustainable point: at one point where the country has too much public debt the country is trapped in the "debt trap". At that point there simply is no way that you can get out because the interest of the debt alone is impossible to be paid without contracting more and more debt.
That is what happened to Greece, for example, where a state default took place.
Now people know that states are going to default so nobody wants to buy government bonds anymore: so the states are basically forcing the banks to buy govt bonds (with a last resort using the BCE as a "bad bank").
So when a country defaults, lots of banks are suddenly virtually bankrupt: they either need a bail-out or go bankrupt. Should they go bankrupt that would deal a huge blow to the economy. Nobody wants Deutsche Bank or BNP Paribas going down: that would probably mean civil war and the end of the western world as we know it.
So states are basically forced to bail out these banks. But, guess what, states are already way too indebted. So they're contracting even more debt, making it even more likely that they'll default.
Cyprus' banks happened to hold lots of govt bonds from Greece. Hence they got fuxx0red when Greece defaulted on part of its state debt.
Now of course if Cyprus defaults, more banks are going to be bankrupt and need a bailout or trigger massive civil unrest... etc.
Because after Cyprus it's going to be Spain, Italy, Portugal... In 2014 it's very likely that France won't be able to finance itself on the market at reasonable rates.
Nigel Farage explained this quite well in a talk in front of the european parliament: this cycle / state default / bank bailout / more state default is endless.
So the eurocrisis is first and foremost a crisis due to the various governments being ruled by clueless monkeys who can't count ("It's all lawyers, lawyers, lawyers" as Neil deGrasse Tyson wrote) and who've been hiding state debt behind growth.
Add to that a gang of banksters sharks always willing to try to create more money out of thin air with crazy leveraging and you get the crazy situation we're in.
It's now gonna end well because if you try to "analyze the curves" you realize we're going into a wall.
There is no way out.
Now of course the various politicians, most notably the socialist ones, are trying to tell us it's all the fault of liberalism and banksters but the cold hard truth is that when you run a country always on deficit at one point it becomes unsustainable.
Sweden got this in 1993 and in 20 years they went from a public sector representing 67% of the GDP to 49% today, meanwhile lowering they public debt from 70% of the GDP to 30%.
And that's a socialist country. And that's something socialists in the eurozone simply do not understand: the public sector is way too important, the private sector is way too taxed and we're going into a wall.
The solution is less state.