昨天來登陸MSN的時候，突然登陸不上了，出現了問題。
主要是時間不對的問題。
最有可能的原因： 系統時間錯誤 返回信息：80048820,總是說防火墻設置阻止MSN的連接。但在MSN的網絡連接測試中都是成功。 解決方法：系統日期不對造成的！！！！，請你認真查看是否在你升級到MSN7.5以后，系統日期變成了2004年，如果是直接將系統日期改成現在的時間。 點擊右下角系統時間設置為當前正確時間。OK！
下面是解決的方法....
下面引用官方關于該代碼的答復：
How to fix error code 80048820
Problem description
When you start MSN Messenger you cannot sign in, and you get the message:
Sorry, we were unable to sign you in to the MSN Messenger at this time. Please try again later. To let us try and troubleshoot the problem, click the Troubleshoot button. 80048820
Fix this error / possible solution
This error seems to indicate a problem with MSN Messenger's encryption routines.
The usual cause is that the time on your computer is not correct. To correct the time on your computer, double-click the clock in the bottom right of your screen, in the window that appears you should check both the time and date. If you use Windows XP, you can automatically correct the time by clicking the "Internet Time" tab, next click the "Update Now" button.
If you still have problems connecting with the time adjusted, try to run this file. This will make sure MSN Messenger can find all the files it needs on your computer.
中文大概意思：當你的MSN 無法登錄，且提示錯誤代碼為80048820，這種問題一般是由于你的系統時間不對，先校準系統時間，如果仍然無法登錄，可能是由于DLL文件注冊信息丟失，下載這個批處理文件 http://www.msn-problems.com/downloads/register-messenger-dll-files.bat 運行一下，問題應該可以解決

然后教你怎么樣。。。。
This register-messenger-dll.bat file will register DLL files required for Messenger.
To run it simply doubleclick, or click it with right mouse and select Open.

For your safety, it is advised you only download the file from imzers.com
You can always have a look at it's content by opening it with any text editor.

It will execute the following commands:
regsvr32 softpub.dll
regsvr32 Wintrust.dll
regsvr32 Initpki.dll
regsvr32 Dssenh.dll
regsvr32 Rsaenh.dll
Regsvr32 Gpkcsp.dll
Regsvr32 Sccbase.dll
Regsvr32 Slbcsp.dll
Regsvr32 Mssip32.dll
Regsvr32 Cryptdlg.dll

You can also do this by hand. Click Start, and then press Run...
Now type: 'regsvr32 softpub.dll' and click OK or press ENTER.
Repeat with all other lines as shown above.

Have fun using Messenger!