Netflix, the DVD rental service, is suffering from the biggest shipping problem in its history, delaying delivery of those familiar red-and-white envelopes to millions of its customers.

The Los Gatos, Calif.-based company yesterday told its 8.5 million subscribers that it had been experiencing "severe technical issues" that had prevented it from mailing movies and TV shows. The problems began Monday night and halted all shipments Tuesday. On Wednesday, the company was able to send about half the discs subscribers had ordered from its 55 U.S. distribution centers.

"It's comprehensive, and it's affecting our entire nationwide distribution systems," Netflix spokesman Steve Swasey said.

The problem, which he wouldn't identify, has prevented delivery to about one-third of the company's members, or about 2.8 million subscribers, who have sent discs back and are awaiting their next shipments, he said.

According to its Web site, Netflix sends DVDs to members by first class mail, with a postage-paid return envelope, from more than 100 U.S. shipping points. It has operated a shipping center in Honolulu since November 2004.

In a message on its home page yesterday, Netflix said, "We apologize, and we'll be automatically issuing credits to all of you whose shipments have been delayed. Our goal is to ship DVDs as soon as possible and to provide a personalized e-mail update to you if your DVD shipment was delayed."

Netflix, which ships about 2 million discs a day, has missed shipments only one other time since it launched its DVD-by-mail subscription business in September 1999.

That delay occurred in March. Netflix then issued a 5 percent credit in monthly fees to members whose discs were delayed by one day and a 10 percent credit for shipments that were delayed for two or more days.

This time, the company hasn't yet determined how it will make it up to its members.

"There's no set formula because this is only the second time in our company's history that we've missed our shipping date," Swasey said.

So far, the delay hasn't cost Netflix much in the way of consumer satisfaction, said Michael Pachter, an analyst with Wedbush Morgan Securities.

"Most people aren't sitting by their mailboxes on a Wednesday or Thursday waiting for their Netflix movies," he said.

Netflix currently has no estimate of when its technical difficulties will be resolved.

"We have hundreds of engineers working round the clock to fix this problem," Swasey said.

Shares in Netflix rose 68 cents, or 2.2 percent, to $31.84 yesterday.

The Associated Press contributed to this report.