A vulnerability identified in a library included in Windows XP and Internet Explorer version 4.0 and newer can be exploited to cause a DoS (Denial of Service) on certain applications.
The vulnerability is caused due to a NULL pointer dereference bug in Microsoft Shell Light-Weight Utility Library ("shlwapi.dll"). A malicious person can exploit the vulnerability by constructing a special HTML document, which will crash applications using the vulnerable library.
An example was provided in the original advisory:
(html)
(form)
(input type crash)
(/form)
(/html)
Read the full buginfo here:
http://www.secunia.com/advisories/8642/