It couldn't come at a worse time for beleaguered Research in Motion (RIM): Its proprietary wireless network for BlackBerry smartphones experienced service outages in Europe, the Middle East, and Africa on Monday and Tuesday, and now they've spread to North America, too. As a result, BlackBerry users are experiencing email-delivery delays of up to three hours, as well as sporadic access to the web and BlackBerry Messenger.

"Email was updating very slowly or not at all today," said Jeff Giles, a software developer at a Boston-based asset management company who was traveling in Europe this week. "I've not received email in hours, which is not possible."

Giles' experiences are apparently very common. BlackBerry users throughout the Europe, Middle East, and Africa (EMEA) region complained about service outages starting Monday, and on Wednesday, millions of BlackBerry customers in the United States and Canada awoke to similar problems.

RIM on Tuesday blamed the EMEA outages on a "core switch failure." But with service failing in North America now, it's unclear what the underlying cause could be.

"Although the system is designed to fail over to a backup switch, the failover did not function as previously tested," a RIM statement explaining the EMEA outages notes. "As a result, a large backlog of data was generated and we are now working to clear that backlog and restore normal service as quickly as possible. We apologize for any inconvenience and we will continue to keep you informed."

RIM issued separate statements Wednesday to address the new problems in North America and continued outages in EMEA. "BlackBerry subscribers in the Americas may be experiencing intermittent service delays this morning," it noted, while not explaining what happened. "Many of you are still experiencing service problems [in the EMEA as well]."

Although RIM's network for BlackBerry is considered to be secure enough for businesses and quite reliable, it has had issues in recent months: Customers in North, Central, and South America also experienced outages in September, for example.

The high-profile outage comes at a tough time for RIM, which has been hemorrhaging users in recent quarters as it falls further and further behind the iPhone and Android market leaders. Various analysts have called for RIM to dramatically change its strategy and consider ousting its dual CEOs, Jim Balsillie and Mike Lazarus. And its recently released tablet, the PlayBook, is considered a dud.

As is often the case in such situations, the outages have triggered some black humor. One joke making the rounds on Twitter reads, "What did one BlackBerry Messenger user say to the other?" "Nothing."