It’s a rough day for Windows Phone community, as a fair slice of the users of the mobile line are being roughed up by an error in the WP7 Marketplace that is leaving them frustrated.

The error, which renders the Marketplace unusable to some, is yet unknown in its origin. TNW Microsoft has requested a comment from Microsoft on the matter. This post will be later updated to reflect its response.

The problem itself, which stops users from being able to use the Marketplace, has been speculated to reflect Microsoft updating the software itself to allow for the purchasing of Mango-ready applications. But why the company would take down the entire Marketplace for only some users is a relatively strong refutation of that idea.

The error has its own nickname, and is sometimes referred to the ‘b00b’ problem. It only affects Windows Phone handsets that run NoDo or Mango. Or, in other words, nearly every Windows Phone user is at risk.

If the problem becomes more widespread it could affect app sales, perhaps dimming developer enthusiasm (at whatever level it currently resides at). For now we are in wait and see mode. I have not managed to reproduce the error in testing. For those who are curious, the following image details what some are seeing:

marketplacerror4 520x358 Windows Phone Marketplace plagued with c101b00b error

There are reports from several known Windows Phone users that their version of the WP7 Marketplace is functioning as it should; the problem is not universal. As we learn more, we will keep you informed, so stay tuned.

Update: Microsoft got back to us: “We have received reports that some customers are having intermittent problems downloading applications from the Windows Phone Marketplace. We are investigating these reports and addressing the issue as quickly as possible. We apologize for any inconvenience and will provide an update when we have more to share.”