There is a theory in electronics known as "positive feedback" and "negative feedback". The theory goes that in "positive feedback"a small increase in power in one circuit causes a large increase in power in another circuit (Im a bit rusty on exactly the correct phrasing). The converse is also true whereby with "negative feedback" a small decrease in power in one circuit causes a large decrease in power in another circuit. This feedback theory has also been applied to economics whereby with booming economies it is positive feedback that is occuring and with recessions it is negative feedback that is occuring.
The irish economy for the last 15 years has been experiencing "positive feedback loops". Whereby the first good news story of the irish economy was foreign investment in ireland resulting in gradual increases in employment, this then resulted in increasing employment in indiginous industry to service the multinationals, this then caused an increase in employment in the construction industry to build houses for this growing workforce and so on.... So growth in one sector of the economy fuels growth in another, it has been a self sustaining cycle for the last 15 years and was resilient enough to throw off the high tech hiccup in 2001.
"Negative feedback" is the opposite and occured in America from 1929 to 1937 and in Japan from 1990 to the present day. When it becomes established it becomes entrenched and is difficult to break out of.
My own belief is that the irish economy at the moment is still running on the momentum produced by all those "positive feedback" loops. But the circuit that caused the original loop "foreign investment" is drying up and this could be the circuit that also causes negative feedback.