Cubase 8 feedback problem - help please

I am a new user of cubase pro 8 and would appreciate advice how to solve a wicked problem. When I activate the track monitor button on any audio track I get a high frequency feedback sound, with the volume rising to avery high level on the track meter. This is particularly when I activate a sim plugin such as guitar rig or amp sim as an insert on any track.
I don’t understand why this is happening as I am using the same track settings for cubase 8 as the cubase 7.5 version. I am using an e-mu 0404 card, which works just fine for cubase 7.5, which makes me think there is something peculiar to the cubase 8 settings. Help/ suggestions will be gracefully appreciated