“The new iMac has been a huge hit and we are working hard to fulfill orders as quickly as possible.”

That’s the official line Apple (AAPL) public relations is putting out to explain delays that have pushed shipments of the new 27-inch iMacs past Christmas. And indeed, sales of Apple’s desktop computers in October and November were up 74% from the same period last year, according to Piper Jaffray’s Gene Munster.

But customers who took delivery in the weeks after the machine’s Oct. 20 launch tell a different story. “I have been experiencing some problems with the all new iMac 27 inch display,” wrote Belgian user Jan Sampermans on Oct. 27 in the first of 1,279 messages on an Apple support forum entitled New iMac 27inch screen flickering/tearing/shutoff. “In the course of writing this post my screen has flickered 13 times and has gone black 2 times.”

As of Tuesday morning, the discussion thread he started had drawn 198,500 views, and a YouTube video of a stuttering iMac screen had been watched 45,466 times.

Below the fold, a chart tracking this and the other iMac production issues. It was begun by a Canadian Web designer after his 27-inch model arrived with a cracked screen.

Apple has not said what it’s doing to correct these problems. Its online store won’t guarantee delivery of 27-inch iMacs earlier than two weeks from today — that is, until four days after Christmas. According to another heavily subscribed Apple discussion forum (306,255 views), authorized resellers have been experiencing delays of up to two months.

UPDATE: On Tuesday Dec. 22, a day after a federal judge in New York dismissed a class action suit over the issue, Apple released a firmware update to address the problem.

[Follow Philip Elmer-DeWitt on Twitter @philiped]