Error code 80048820 usually occurs when there is a problem with the .NET Messenger service. one or more of the servers providing it might be down or having problems, with as result that you can no longer sign in. This normally won't take longer then a few minutes/hours. For more information you can check the .NET Messenger Service Status
When you start Windows Live Messenger you cannot sign in, and you get error code 80048820 along with the message:
We were unable to sign you into Windows Live Messenger at this time. Please try again later.
Error code: 80048820
Extended error code: 80048412
Please note that the Service Status is known to not always be very accurate, if problems do appear the best thing to do is wait them out. Surely there are many other very interesting things to do. If the error keeps bothering you for over a few days there are some more things you can try below.
Other steps that might help
Check if the time and date on your computer are set correct, as it might confuse Messenger. To verify if they are, double-click the clock at the bottom right of your screen, click ok once/if everything is adjusted right.
If the error continues to appear it is most likely because the Windows digital signatures system is damaged or corrupt. To resolve this you will have to register several dll files that are required for Messenger. You can do this automatically by running a batch file we created or if you prefer by executing the commands yourself.
further details can be found http://www.imzers.com/msn/solve/error-code-80048820