Bad Radio Reception after XM Install

Hopeing someone can help me here. I just installed the SkiFi RF Modulated XM Radio in my car. The XM  is working great...sound could be a little better but I think thats the crappy GM factory stereo. Anyhow, now that the XM is installed I'm unable to get "good" reception on my FM radio stations. It's almost like the RF Mod. is not turning completly off and is causing some interference with the FM radio during nornal radio use. I grabbed the right ignition wire for power and I what I believe to be a good gound wire (checked it with the multimeter) , I have the right GM antenna adaptors and a clean install. Anyone have any ideas??

Here are my 2 thoughts that I need to double check, maybe someone could confirm before I rip it out  again.

1. Is it possible that the Modulator is too close to the Radio...I have it sitting in behind it, very close to the back of the radio.

2. Could having a better ground wire fix this problem? The wire that I tested seems to be a good ground..but you know how that goes.

Any help or advise would be grealty appreciated. Thanks kindly in advance.

-Jeff _rdk

Thanks raydawg357...you can hear the Modulator sort of turning off...but I have used and installed many modulators before and you usually would get a small pop like sound when it was turning on and off. Im not getting that strong pop like sound when I turn it off. I could put in a inline switch for the time being to turn it off completly until I get back from Vacation. I got the Modulator for free...so no chance in returning it.  Does WalMart sell XM...I bet I could return it there!