Cracks in BlackBerry armor

Shares of Research in Motion tumble as investors question whether the device maker can overcome several challenges after warning of lower profits.

The stock slipped 11 percent at the open and didn't improve as the trading day wore on.

RIMM hit a raw nerve when it warned earnings will be down in the current quarter as it beefs up spending to

launch the PlayBook tablet, its answer to the Apple iPad. The PlayBook goes on sale in North America on April 19th.But RIMM has a tough competitor in the iPad. iPad 2 went on sale internationally on Friday, less than a year after the original iPad went on sale.

Hundreds lined up outside of stores in Australia and New Zealand.

ALEX LEE, FIRST IN LINE, SYDNEY, AUSTRALIA SAYING:

"I'm actually - I have an iPad 2 already. I have had previous iPads and I am actually getting an iPad for my sister and one for auction."

But waning demand for the once ubiquitous BlackBerry is a bigger worry. Market share of the device is falling steadily as the iPhone and smartphones powered by Google's Android software gain in popularity.

An upgraded BlackBerry device is not expected until the back end of this year.

Conway Gittens, Reuters