Strong signals and signal reflections , multi path.
Try a variable attenuator , # 1296F , to ' dial down ' the signal strength.
http://www.solidsignal.com.
Also can try a Winegard HD7210P directional antenna aimed at about 280 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
As always the starting antenna aim direction is --> the starting antenna aim direction.
The antenna can be turned to the left and right to find a direction that provides better reception.
Can also call the Tv station KUSA , chat with the engineering department and they can help.
Yes KUSA and KMGH both know about reception problems with VHF channels 9 and 7.