HTC Droid Eris :: Last.fm - Pandora Issue When Plugged Into My Car's Aux Port

I'm having a really strange problem when listening to Pandora or Last.fm radio on my Eris (haven't tried music off my SD card yet, still have it all on my old phone) through the aux port on my Sony headunit.
When it plays, sometimes it will skip to the next song at random and even make a PHONE CALL to the last number on my call list! All while the screen is locked. Yes, the phone will unlock, make a call, and skip songs without me touching it. I was thinking it's the cable (cheap-o I got from dealextreme.com) but my friend's Motorola Droid works fine in my car. I jiggled the cable around where it was plugged into the phone and it skipped a song. So I tried plugging it into the desktop HD radio's aux port at work, and it works fine. Jiggling the cord did nothing. So could it be the cord? Or is it my headunit? The thing is, my LG Chocolate2 worked just fine in my car (with an adapter plug) with the same cable/radio.