Rihanna might have the No. 1 spot on the British album charts, but that doesn't mean she can show up late to her U.K. gigs -- as she learned last week, when an angry crowd booed her after she took the stage at London's O2 Arena an hour after the concert's scheduled 9PM start time.

This comes a month after an almost identical incident at the same venue, and offers the latest suggestion that the rumors surrounding Rihanna's reported "exhaustion and stress" might bear an uncomfortable kernel of truth.

"She didn't come on till 10, leaving the audience waiting an hour. She then got booed and her singing was rubbish," complained a disgruntled fan in attendance at last week's show. "The show was unnecessarily raunchy and inappropriate. When we left halfway through the show, along with loads of other people, staff were handing out information on making complaints."

Whatever Rihanna's personal issues might be, they don't seem to be affecting sales of her latest album, 'Talk That Talk,' which debuted at No. 3 on the Billboard Top 200 after its Nov. 18 release, moving nearly 200,000 units in the process. The album's first single, 'We Found Love,' topped more than 30 charts worldwide -- and broke a Billboard record -- while the follow-up, 'You Da One,' is already comfortably ensconced in the Top 20.

Rihanna will have a chance to make it up to her London fans when her tour brings her back to the O2 Arena for a three-night stand on Dec. 20. Until then, she'll be on the road throughout Europe, making stops in the Czech Republic, Italy, Spain, and Switzerland.

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