Everything was set for Britney’s show at Vancouver’s GM place. The fans were ready, the star was ready and everything looked set for another stop on the Circus tour. Lights dim, the crowd goes wild, the Perez Hilton video introduces Spears – it’s showtime!

But, sometimes even the best laid plans of tour managers and pop stars go awry. In this case, Britney walked off stage after two songs.

As fans waited screamed, “Britney! Britney! Britney!,” an announcement over the public address systems told the crowd that a ventilation problem had caused the unforeseen break in the action, according to a blog posting in the Vancouver Sun.

“It’s become uncomfortable and unsafe for the performers, including Ms. Spears. The show will resume as soon as the air around the stage is clear.”

While the Sun doesn’t explain what the problem was with the “air around the stage,” another blogger gave a more exact description.

“Seems as if there are too many concert goers smoking BC bud and she and the dancers cannot perform because of it!”

So it looks as if that ol’ devil weed may have been the root of Britney’s ventilation problem last night.

Britney returned to the stage at 9:05 p.m. and finished the show. Later, the star’s publicist issued an apology.

“We want to apologize to all the fans who attended our Vancouver show tonight for the brief pause in Britney’s set. Crew members above the stage became ill due to a ventilation issue.”

Next stop is tonight in Tacoma, Wash. Ventilation permitting.

Click here to read the posting in the Vancouver Sun.

Click here to read the publicist’s announcement.

Click here to read the “BC bud” remark at Mia’s Meddling.