Please sign in again. iTunes Match has encountered an error.

I'm having the same exact problem when I start iTunes. When I sign out and sign back in, it is as if iTunes Match never matched anything on my computer. iTunes Match is turned off, and when I turn it on, it asks me to add my computer ... again. That takes me through the whole 3-step process of identifying and matching my library. Given that this seems to be a multiple-day experience, the thought of having to rematch everything from scratch again is completely implausible.

It's not as if my library has disappeared from the cloud. I can access all my songs through my phone from the original match. Very frustrating, especially now that I'm trying to go through the process again, I'm now experiencing the iTunes crash during Step 2 (when/if it gets to Step 2). What a disaster.

Getting the same error message. Nothing new to add except there seems to be an error loop (sign out - sign in - crash - sign out - sign in - crash) that not only locks up iTunes, but my entire machine.

I was able to resolve my problem ... for now. The problem seems to be tied to iTunes error 42408, which I believe is related to Genius. At any rate, I restarted my computer, disabled Avast anti-virus program and also turned of AudioGalaxy, the music-streaming service I'd been using prior to Match. Everything worked as it was supposed to after that.

I honestly don't know if shutting off the aforementioned programs were the solution. I get the 42408 error intermittently with no clear understanding of what it is or why it only occurs sometimes. But I do think this is a problem related to Genius and possibly tied to Apple's servers being tied up. Whatever the case, this is a show stopper if the problem persists.

I have a similar problem, please sign in again and all that... but I dont get the error 42408...

When I start iTunes, there's a little cloud icon next to my Music Library, but there's a sort of lightning bolt across it. If I click on the icon, it turns into a sort of silver spinning texture, but nothing happens.

I have to actually turn iTunes Match off and back on in order to get it to work properly.

In related news, I just installed iTunes on my work PC and linked it with my iTunes account. It can access iTunes Match on startup with no problems.

Now I'm wondering if it was my home PC's network card that was causing problems. (The Bigfoot Killer network cards have caused problems with iTunes in the past because of the QoS trickery used in the drivers). I'm gonna update my network drivers tonight and see what happens.

No help. Still have to disable iTunes Match and turn it back on again on my home PC to get the crap to work properly.

I am having the same issue with my Windows 7 home computer. It tells me that iCloud has encountered an error and that I should log out and then log back in. When I do, it starts the whole process over, asking me if I want to add this PC and then the three-step process. It's done this repeatedly.

I recognize another "me too" post isn't inherently helpful, but if it helps Apple figure out that it is a problem for a lot of people, then Apple might help. So "me too". Running Windows 7 x64.

I am running all the latest Apple Lion Software and all my devices are updated: iMac, MacBook Pro, iPhone 4, and iPad 2. I PAID for iTunes Match (two weeks ago) and keep getting the following message EVERYtime I try to log in:

Please Sign In Again: iTunes Match has encountered an error. Please choose Sign Out and then Sign In from the iTunes Store menu and try again.

It really doesn't matter HOW MANY TIMES I sign in and out. It's a very annoying merry-go-round. I love Apple and its products. But if iMatch wasn't ready to be launched and WORK PROPERLY, then don't launch it!

One more "me too", its happening on both my home computer (windows 7 x32) and my work computer (windows 7 x64). although it has gone through most of my home collection before stuffing up and it appears some music has uploaded as the number to upload has reduced i cant see any sign of it working on any of my devices. incl iPad and iPhone.

Very disappointing but hopefully they fix it soon.

I have this problem as well, but only on one of my two computers. Uninstalled and reinstalled iTunes, but still get this everytime I restart iTunes. My other computer works just fine. Both are running Windows 7. There are sporadic references to this problem on various support sites, but no one seems to have a solution. Help!

Since there hasn't been a "me too" post today, I might as well report the same thing. Running Windows 7, latest iTunes, and paid for Match about a month ago. Whenever start iTunes, I have to sign out then back in before match or the cloud work with iTunes. I also have to re-add my computer, although that doesn't take very long now.... not like it originally did. Anybody?

Okay, here's another me too..

Just bought iTunes Match today because I'm in Canada

And right after I paid for it, I can see the little cloud icon under the iTunes store and it ask me to add this computer, then I get the same message as mentioned above.

And ONE THING MORE is for now I can't even see the cloud icon and the open iTunes match, it just disapper, but in my itunes account page, it says my iTunes match is there.

Anybody?

Me too, etc. Yeah I think Match might have borked under the strain of all the new users.

Another 'me too' in New Zealand. Macbook Pro fully up to date. I've paid for iTunes Match, but I get the same error message whenever I try to activate it. Hopefully Apple will realise there's something wrong and respond soon.