A massive service outage of Research In Motion Ltd.'s BlackBerry e-mail that frustrated thousands of users across North America earlier this week was reportedly caused by a "non-critical" software upgrade. The information was reported on the Wall Street Journal's Web site on Thursday.

The crash left politicians, lawyers, business executives and other so-called "CrackBerry" addicts without wireless e-mail service on Tuesday night and into Wednesday.

The disruption was caused by the implementation of a "new, non-critical system routine" that hadn't been tested sufficiently, the Journal reported, citing RIM.

RIM has about 8 million subscribers that use its BlackBerry devices.