Disgruntled BlackBerry users took to Twitter this week following several service outages that have reportedly now affected U.S. subscribers.

What began as an issue impacting some BlackBerry customers in the Europe, Middle East and Africa regions earlier this week spread to the United States by Wednesday, Research In Motion officials said, pointing to a “core switch failure” within RIM’s infrastructure.

In a service update post Tuesday, RIM officials wrote, “The messaging and browsing delays that some of you are still experiencing were caused by a core switch failure within RIM’s infrastructure. Although the system is designed to failover to a back-up switch, the failover did not function as previously tested. 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 sincerely apologise for the inconvenience caused to many of you and we will continue to keep you informed.”

Early Wednesday, company officials pledged, “the resolution of this service issue is our Number One priority right now and we are working night and day to restore all BlackBerry services to normal levels,” acknowledging that BlackBerry subscribers in the Americas could be experiencing intermittent service delays.

The disruptions affected Blackberry users in Europe, the Middle East and Africa, India, Brazil, Chile, and Argentina, the Associated Press reported.

Meanwhile, frustrated smartphone users headed for Twitter to vent about their frustrations, “questioning why the company took so long to restore services,” the AP said.

KineticalDummy tweeted, “Blackberry deserves an award for being the most useless smart phone of all time. Of all time...”

Meanwhile another angry user, Jeeves Williams, made a crack about Steve Jobs’ causing the disruption in his afterlife: “Steve Jobs’ ghost sneaked into RIM's data centres and tripped a few switches to cause the BlackBerry outage. Trolling from beyond the grave.”

In Britain, Vodafone UK told customers via Twitter that service was not fully restored, according to the AP, adding that Rival T-Mobile UK blamed “a European-wide outage on the BlackBerry network” which it said was affecting all mobile operators.

There also were reports of problems elsewhere in Europe, such as Spain, the AP said.

On Oct. 12, RIM promised, “We are working to resolve the situation as quickly as possible and we apologize to our customers for any inconvenience. We will provide a further update as soon as more information is available.”