终于能用msn了，尝试过网上的各种方法，只有下面这个是work的！分享给和我一样遇到vista下msn无法登陆错误81000378的人……

Error: 81000378
When you try to sign in to MSN Messenger, you receive the following error mes
sage:
You cannot use Messenger at this time because your contact list is not avail
able. Please try again later 81000378
PROBABLE CAUSE
The following condition may apply:
• For MSN Messenger: The Address Book Clearing House servers or th
e Contacts List servers are unavailable because of high-volume traffic or bec
ause the servers are down.
• For Windows Live Messenger: You are unable to connect to the con
tacts servers and hence are unable to download your contact list.
TROUBLESHOOTING STEPS
1. Identify the version of Messenger you are using. To do this, click on
the Help Menu and choose “About Messenger”.
a. If you are using version MSN Messenger version 7.5 and lower, you ma
y be experiencing this error because of a temporary service issue. Please vis
it the following web site to check for the latest Messenger service status:&n
bsp; http://status.messenger.msn.com/Status.aspx
Note:  If the Messenger service status page does not indicate that ther
e are any service issues then please try to sign in after a few minutes. If t
he Messenger service status page does indicate a service issue with the Messe
nger service then please check this page for updates until the service issues
has been resolved.  Once the service issues has been resolved you can t
hen try to sign in to Messenger.
b. If you are using Windows Live Messenger, please proceed to the next
steps.
2. If you are using Windows Live Messenger, the most likely reason you a
re experiencing this error is because Messenger has not been able to download
your contact list and you are unable to connect to the Contacts service to d
ownload your contact list. Try the following steps:
a. Adjust your Microsoft Internet Explorer security settings:•&nb
sp;Start Internet Explorer. 
• On the Tools menu, click Internet Options, and then click the A
dvanced tab. 
• In the Security section, make sure that the following check box
es are set correctly:
          o Clear the Chec
k for server certificate revocation check box. 
          o Select the Use
SSL 2.0 check box.  
          o Select th
e Use SSL 3.0 check box
• Click OK to close the window.
b. If you are using Windows Live Messenger on Windows Vista, click on S
tart and type in each command one at a time in the Windows Vista search box l
ocated on the Start menu.  For Windows XP click on START, select RUN and
type in each command below one at a time and click the OK button. After each
command is executed successfully, you will receive a "DllRegisterServer succ
eeded" message. Wait until you receive this message before you run the next c
ommand.
• REGSVR32 softpub.dll 
• REGSVR32 wintrust.dll 
• REGSVR32 initpki.dll 
• REGSVR32 Rsaenh.dll 
• REGSVR32 Mssip32.dll 
• REGSVR32 Cryptdlg.dll 
• REGSVR32 Dssenh.dll 
• REGSVR32 Gpkcsp.dll 
• REGSVR32 Slbcsp.dll 
• REGSVR32 Sccbase.dll 
c. If you are connecting from a corporate network and are experiencing
this error, it is likely that your corporate proxy may be blocking access to
the contacts domain Please request your network administrator to:
• Permit connections to https://*.contacts.msn.com through networ
k proxy.
• If the proxy has rules based on user-agent string, please ensur
e that connections with the HTTP user-agent string “MSN Explorer/9.0 (MSN 8.
0; TmstmpExt)”  are allowed to connect through the proxy.
3. If the issue still persists, please provide us the connectivity log s
o that we can review it to determine the issue that is causing this error to
be returned. To do this, follow these steps:
a.  Turn on connection logging if this feature is not already turned on
:
• Start Messenger but do not sign in.
• On the Tools menu, click Options.
• In the left navigation bar, click Connection.
• Click Advanced Settings.
• Under Connection Logging, make sure that the Save a log of my s
erver connections to help troubleshoot connection problems check box is selec
ted.
• Click OK.
b. To sign in to Messenger again, click Sign In and wait until the erro
r message appears again. The new connectivity log file, MSNMsgr.txt, is gener
ated when you try to sign in.
• To access the generated MSNMSGR.TXT file.
• On the File menu, click Open Received Files.

• A windows explorer window will launch. Locate the MSNMSGR.TXT fi
le in this folder.

来自http://cc.msnscache.com/cache.aspx?q=72378939678472&mkt=zh-CN&lang=zh-CN&
w=89194b55&FORM=CVRE6