Although the post has aged, the information contained is still helpful in solving the issue I was having that was really similar to this. I have an inexpensive USB microphone, that I had moved from my original recording setup position, and I had hung it from the strap on the amplifier as I used to do with my old standard microphone. That's when the weird noises began!
I use a soft styrofoam, similar to a kids pool floaty but with a hole down the middle and a slit cut from end to end. Then I run the mic cable through the hole or slit and shove the microphone into the hole at one end. I face my 2 amps towards each other about a foot apart (Not recommended if you use both at the same time!) and place the mic on the floor in a position near which ever amp I am using. The soft foam seems to reduce vibrations caused by the amp which seems to have caused the weird noise or interference I was getting. The positioning of the amplifiers allows me to reduce outside noise by boxing in the mic between the amps.
I didn't need to go as far as purchasing the interface which was spoken of in the comments. I did download the Cakewalk software and I am enjoying using it over the Audacity software I had previously used.
Thanks for the tips and I hope this post helps someone else in the future.
