Hi and welcome :-)
Ok, Windows is probably looking for a "startup" element that Quicktime had and as you have deleted QT it cannot find it. My suggestion is to go into msconfig ( guide here:
http://netsquirrel.com/msconfig/ ) > go to the "Startup" tab and un-tick any references to Quicktime, QT, QTtask etc.
Re-boot and when the box comes up, check the box to say "don't show again".