other account on hold since last year

[Rolig Loon]

That sounds very much like someone is running a scam on you. That is not a normal sort of messagew for Linden Lab to send.  As far as I can tell, that is not a listed phone number for Linden Lab either.  I suspect that if you call, they will sound helpful and will ask a series of questions that will end with you giving them access to your account.  It may be smart to treat this as an attempt to compromise your account. So ...

Go to your dashboard at secondlife.com >>> Account now and change your password.  Then follow these instructions >>> http://wiki.secondlife.com/wiki/Linden_Lab_Official:Account_Security  .  Your account really wil be placed on hold while Linden Lab investigates, but they should be able to set your mind at ease.

[Rolig Loon]

That sounds very much like someone is running a scam on you. That is not a normal sort of messagew for Linden Lab to send.  As far as I can tell, that is not a listed phone number for Linden Lab either.  I suspect that if you call, they will sound helpful and will ask a series of questions that will end with you giving them access to your account.  It may be smart to treat this as an attempt to compromise your account. So ...

Go to your dashboard at secondlife.com >>> Account now and change your password.  Then follow these instructions >>> http://wiki.secondlife.com/wiki/Linden_Lab_Official:Account_Security  .  Your account really wil be placed on hold while Linden Lab investigates, but they should be able to set your mind at ease.

[Madelaine McMasters]

I agree with Rolig, that you're probably being scammed. However, I'm wondering what exactly you were logging into when you got the message. If you were logging into your web dashboard, it's quite possible you followed a phishing link to a non Linden website that tried to get your login credentials. If that actually happend, you should immediately contact Linden Lab via a support case, here...

https://support.secondlife.com/create-case/ 

Select "Account Issue" from the first drop down and "I believe my account has been compromised" from the second. Fill in the requested information, citing MLPROCKS13 as the compromised account. LL will lock it, then ask you for proof that you own that account. Once that's been done, you may get your account back.

If you were logging into SL via a viewer, I can't explain that message.

Do not visit the Second Life website via any links that were given to you in a message of any kind. Either use an old, trusted bookmark to secondlife.com, or type it in yourself. That way, you can be certain that you are not visiting a spoofed site that's trying to obtain personal information from you. You should even double check the link I gave you above, to make sure it really and truly goes to secondlife.com.

Good luck, be safe!

ETA: Googling the phone number pops up a couple threads from years ago telling stories suspiciously like your... and links suspiciously like those I find when I google the phone numbers of unrecognized incoming calls on my phone (which I do not answer). They usually turn out to be marketing/spam numbers.