* Euro is strong shield but also has drawbacks

* Slovak firms suffering due to euro adoption

* Labour costs up by more than 50 pct since 2005

* Case serves as example to other euro zone aspirants

By Martin Santa

KRALOVSKY CHLMEC, Slovakia, Nov 11 (Reuters) - When Slovakia adopted the euro in January, Alexander Joszay loved driving across the border to Hungary, where financial crisis had weakened the forint to deliver lower prices for euro-earners.

But the factory where the 58-year-old maintenance man worked liked the idea too. It sacked Joszay and other Slovaks a few months later and moved across the border.

"There was not just the single positive thing of people taking advantage of the exchange rate," said Joszay, who worked for car parts firm MBE in this eastern Slovak town.