This is a worm that spreads itself by sending links to your contacts in messengers like Yahoo, MSN, AOL and Windows Live messengers. It disables Registry Editor and Task Manager. It changes the Internet Explorer (IE) home page and also modifies registry such that you cannot change the homepage address.
Here are simple steps following which you can get the worm removed from your system:
1) Download this file:
http://avsharath.googlepages.com/DisableW32Sohanad.vbs
2) Double click on the downloaded file, it will execute to restore from the damage done to registry by the worm.
3) Restart your system.
4) Delete the file svhost32.exe from your Windows folder( If it is present).
5) Delete the file svhost.exe from your Windows folder( If it is present).
And the silly worm's story ends!!!
You can now use the Yahoo/MSN messenger peacefully

.
By the way, I have a suggestion for you: Use
Firefox browser to avoid such worm
attacks in future. It is much more secure, you can find it at:
http://mozilla.com/firefox
More information on this worm
in the TrendMicro virus Information on this worm.