This help may be beyond the scope of what is easily accomplished in an
online forum such as this one.
In my experience, this issue is caused by the permissions being altered (by
the spyware) on the registry key where the scan hangs up.
We have to be a little cautious about some "hangs" with Microsoft
Antispyware--there are reports of file scanning issues that sit on a given
file for 1/2 hour to perhaps more than an hour .
It is possible to fix the permissions issue. In XP Home, you must sign in
in safe mode as "administrator" to take ownership or change permissions.
Rather than working through the details of how to do this, if the bug has an
automated removal tool available from an antivirus vendor, I'd strongly
recommend using such a tool--simpler and safer.