From the great website (I'd bookmark it):
http://www.theeldergeek.com/remove_previously_deleted_app_
listings.htm
Remove Invalid Listings from Add/Remove Programs
There are a number of reasons why an application may
remain in the Add/Remove Programs list long after the
application is gone from your computer. One of the most
common reasons is using the uninstaller from the listing
on the All Programs section of Start Menu, but whatever
the reason it remains there are ways to remove the
invalid listing.
Method I: This method avoids editing the registry and
should be tried first.
The easiest way is to open Add/Remove Programs and select
the listing for the program you know has already been
deleted. Select the application and click the Remove
button. Since there is no application to 'remove', the
process will time out and you'll be presented with an
option to remove the entry.
Method II: This method involves editing the registry.
Make sure to have a verified registry backup before
editing the registry. Help with backing up the registry
is available here.
Select Start > Run
In the Open: line type regedit and press Enter.
Navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersi
on\Uninstall
The Add/Remove Programs list is built from the keys
listed beneath the Uninstall folder.
Locate the key for the program that has been uninstalled,
right click the key and click Delete.
Clicking the keys in the left pane and looking at the
information provided in the right pane can help in
identifying the associated programs. Err on the side of
caution in this operation. Once the key has been deleted
it's impossible to use Add/Remove Programs to uninstall
if you make an incorrect selection.
