Expired certificates

[<1tgeye () surewest net>]

We have an IIS server with an old certificate that has expired.  We do not use it anymore and I am arguing to remove it 
from the site.  Other people are saying it doesn't hurt anything and just leave it there.

Can anyone give me a reason why an unused but expired certificate could cause a security risk?  I would like to add 
that to my argument why it should be removed.

-------------------------------------------------------------------------
This List Sponsored by: Webroot

Don't leave your confidential company and customer records un-protected. 
Try Webroot's Spy Sweeper Enterprise(TM) for 30 days for FREE with no 
obligation. See why so many companies trust Spy Sweeper Enterprise to 
eradicate spyware from their networks.
FREE 30-Day Trial of Spy Sweeper Enterprise

http://www.webroot.com/forms/enterprise_lead.php
--------------------------------------------------------------------------