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80048820

Error code explanation and possible solution

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

This is how the Service Status looks with a normal situation
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.
Automatic solution

First you will have to download this zip file which includes a batch file that can register the dll files for you. After downloading unzip it and run register-messenger-dll-files.bat, a black screen will pop up and update you on the process. When done your Messenger should work again!
Manual solution

First open a run window by clicking start, then run. Now, type the following command and press enter:
regsvr32 softpub.dll Wintrust.dll Initpki.dll Rsaenh.dll Mssip32.dll Cryptdlg.dll
If you use Windows XP you should open another run window after running the previous commands then type the following command:
regsvr32 Dssenh.dll Gpkcsp.dll Slbcsp.dll Sccbase.dll

The run screen where you can execute a command in Windows
In previous cases we found Norton Internet Security to be the cause of this error. Normally provided removing and/or reinstalling it fixes the problem.