昨天来登陆MSN的时候，突然登陆不上了，出现了问题。
主要是时间不对的问题。
最有可能的原因： 系统时间错误 返回信息：80048820,总是说防火墙设置阻止MSN的连接。但在MSN的网络连接测试中都是成功。 解决方法：系统日期不对造成的！！！！，请你认真查看是否在你升级到MSN7.5以后，系统日期变成了2004年，如果是直接将系统日期改成现在的时间。 点击右下角系统时间设置为当前正确时间。OK！
下面是解决的方法....
下面引用官方关于该代码的答复：
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：当你的MSN 无法登录，且提示错误代码为80048820，这种问题一般是由于你的系统时间不对，先校准系统时间，如果仍然无法登录，可能是由于DLL文件注册信息丢失，下载这个批处理文件 http://www.msn-problems.com/downloads/register-messenger-dll-files.bat 运行一下，问题应该可以解决

然后教你怎么样。。。。
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!