MS reply:
a. If Windows Live Messenger is running, right-click the Windows
Live Messenger icon in the notification area at the far right of
the taskbar, and then click Exit.
b. Open a Command Prompt window:
- click Start, click Run, type cmd, and then click OK.
c. At the command prompt, type CD, and then press
ENTER.
d. At the command prompt, type the following command, and then
press ENTER:
CD %appdata%\microsoft
e. At the command prompt, type the following command, and then
press ENTER:
CD "MSN MESSENGER"
f. At the command prompt, type the following command, and then
press ENTER:
DEL /S ListCache*.dat
Note: The "S" is uppercase.
This command deletes all .dat files whose names begin with
"ListCache" in all subfolders. You may see a list of the files that
are being deleted.
g. At the command prompt, type exit, and then
press ENTER.
h. Restart Windows Live Messenger.