A number of BlackBerry handheld wireless devices <A HREF="http://news.zdnet.com/2100-1035_22-5758043.html?tag=zdnn.alert">experienced service problems</A> on Wednesday, marking the second time in less than a week that the popular devices lost their data connections. A RIM representative said a hardware failure Wednesday triggered a backup system that operated at a lower capacity "than expected." Service has been restored, she said.