When Marvel and Comixology teamed up for a promotion offering 700 free Marvel digital comics—available only for a two day period—they probably thought it would get a lot of attention.

They were right. It also caused the Comixology servers to go into crisis mode from almost the moment the promotion—dubbed Marvel #1—was announced at Marvel’s Sunday SXSW panel. After nearly 24 hours of Comixology’s entire site being unavailable, the promotion had to be suspended by Monday afternoon.

The initial idea was irresistible for current and potential Marvel readers: 700 comic books, mostly first issues of scores of series, many by popular creators—Joss Whedon, Stan Lee, Jeph Loeb, Brian Bendis, Matt Fraction, Kevin Smith, Jonathan Hickman and many more—would be available for free digital download. Included in the list were the latest #1s from the hot Marvel NOW! relaunch.

Unfortunately, as soon as the news appeared Comixology’s servers began to slow down, unleashing a twitter storm of complaints. Althought some customers managed to get their comics (some lucky ones all 700), many users who managed to login got error messages. While some people were able to download their comics via the iPad app Sunday night, by Monday morning, as news of the promotion hit the highly popular tech sites, the site become entirely unavailable.

The promotion was originally planned to run until 11 pm edt on Tuesday, March 12th. However, Comixology CEO David Steinberger announced that it was being suspended after technicians spent most of Monday trying to get the servers working properly. Both the official Comixology twitter account, a special help account and Marvel’s own feed were full of pleas to stay patient as technicians tried to manage the demand.

Steinberger released a statement on the suspension on Monday afternoon. “We expected a high degree of excitement for the Marvel initiative–and had believed ourselves prepared—but unfortunately we became overwhelmed by the immense response. We’re still struggling to keep our systems up.” Although the team was working around the clock, he said, “To that end, we’re pausing the Marvel Comics #1 promotion for the time being. For those of you that want to take advantage of the offer—you will get your comics!”

Marvel was not the only publisher affected by the problems. Comixology is the #1 digital comics distributor, with more than 100 millions comics downloaded. But during the slowdown, other publishers—who were unaware the Marvel #1 promotion was going to take place—were unable to sell their own digital comics. “We're not happy at all right now,” one publisher who requested anonymity told PW.

Although Marvel had hinted earlier that the promotion might be continued beyond the original two day run, in a later statement, Marvel said only that “When we have further updates from our partner, we will share them.”

Until the server meltdown, SXSW had been a big success for both Comixology and Marvel. Comixology rolled out its Submit portal where indie comics creators can upload their comics for conversion for digital sale.

Marvel unveiled an ambitious slate of several digital initiatives including, starting in July, a slate of original Infinite Comics featuring character such as Wolverine. The comics are fully optimized for mobile, and the publisher’s first foray into weekly digital content.

Marvel also announced Project Gamma, a partnership with Momentum Worldwide and CORD to bring adaptive audio soundtracks to digital comics. Earlier in the week, Marvel updated their Marvel Unlimited subscription service which allows users to access a library of back issues for $10 a month. Previously available only on the web, the program is now available on mobile devices via the Marvel Unlimited App.

This last program, too, was released with some hitches, as many users complained they didn’t have access to the entire library via the app.