Andrew Lilico has written a great article for The Telegraph on the dangers of deposit insurance:

In a classic 2005 paper from the highly authoritative Journal of Monetary Economics, Asli Demirgüç-Kunt and Enrica Detragiache investigated the question “Does Deposit Insurance Increase Banking System Stability?“  Their answer, based on an empirical study of a large panel of countries from 1980 to 1997, was that it does not; in fact, as they put it: “explicit deposit insurance tends to be detrimental to bank stability”.

I recommend the whole article.