According to news reports, Research in Motion (RIM) says that the two BlackBerry outages - one last week and one this week - appear to be caused by flaw in recently released versions of Blackberry Messenger software.
This story in PC Magazine quotes a RIM press release saying that the:
"Root cause is currently under review, but based on preliminary analysis, it currently appears that the issue stemmed from a flaw in two recently released versions of BlackBerry Messenger (versions 220.127.116.11 and 18.104.22.168) that caused an unanticipated database issue within the BlackBerry infrastructure."
"RIM has taken corrective action to restore service."
Yesterday, Blackberry users across the Americas could use their phones to make calls and receive text messages, but were not able to receive messages or chat via BlackBerry Messenger.
RIM is telling users to upgrade to BlackBerry Messenger versions 22.214.171.124.