goto the following above link download the latest version of windows live messenger.
First goto your add/remove programs in your control panel remove windows live messenger, then restart your computer now install the newest version of it and see if this helps fix the issue.
also make sure you computer meets the minimum requirements of windows live messenger.
these are as follows.
Microsoft Windows XP SP2 or later, or Windows Vista
Windows Live programs do not support Windows XP Professional x64 Edition. Windows Live Family Safety does not support 64-bit editions of Windows.
Minimum 800 MHz processor
Minimum 128 MB of RAM (256 MB or more recommended)
Internet Explorer 6 or later
Internet functionality requires dial-up or broadband Internet access (provided separately). Local or long-distance charges may apply.
Minimum 800 x 600 screen resolution (1024 x 768 or larger recommended)
These components are required and will be downloaded and installed if they’re not already on your computer.