Regling and Watson (2010), in their government commissioned review of the Irish banking crisis, highlighted the massive growth in short term bank borrowing as a cause of Ireland's financial crisis. At the end of 2003, the two largest Irish banks (AIB & BOI) had €11.1 billion in short-term securities of 12 months or less remaining duration. By the end of 2006 this had increased to €41 billion. The banks were reliant on benign wholesale markets in order to roll-over such borrowings.
Wholesale markets began to dry up in August 2007. Northern Rock, the UK bank, failed the following month. The heavily indebted Irish banks, operating with very high loan-to-deposit ratios, began to experience liquidity problems. In 2008 these liquidity difficulties deepened, especially around mid-March, when the investment bank Bear Stearns was rescued by the US authorities. By September 2008, short-term liquidity was in crisis, particularly in the aftermath of the Lehman Brothers bankruptcy (Governor of the Central Bank of Ireland, 2010).
So in a nut-shell the Irish banks have a asset-liability mis-match... effectively using short-term money to fund long term positions (i.e. mortgages). The cost of short-term money has shot-up, so when the banks go back to re-finance (or roll-over the short-term money) they are getting squeezed massively... leading to losses on trackers.