first, what program (specifically) did you install and from where?
Sounds more like a worm than the real flash... www.macromedia.com
is the site to get it from.
Second, open regedit, navigate to :
Look there to see if you see anything strange. Also look in Runounce. Then Look in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es for anything that might be linked. You can also check startup from the start menu for possible connections.
Tell us if you find something you can't get rid of...