Audio switcher

I've built a small audio switcher box that takes either a 3.5mm jack from my PC or two RCA (L+R) from my PS3 and outputs to a second 3.5mm jack that goes to my speakers. It's a very simple design - a 3P2T switch that switches everything (ground, left, and right) between the two. The sound from my PS3 works perfectly when I switch to it.

However, no matter which way I try to wire up the other phono jack, the sound comes out muffled when I switch over to my PC. I figured I might have set the jack up wrong (wired L to GND and GND to L or something) but it all looks fine. I've tried switching them round just to test, but it still does the same thing. I've tried using my headphones instead of my speakers, but the same thing happens. It's not the audio cables either, since they've been tested for other stuff and they work fine.

Anyone got any ideas what I've done wrong?

Can you post a schematic please?

It's a very interesting project, and I'm sure it'd help others to help you out.

D'oh! Turns out my box was working absolutely perfectly. BOTH of my audio cables turned out to be bust, with an intermittent fault. When I moved them to the other system, they got squashed against the wall a little which meant they worked OK. I got my soldering iron and scope out for nothing!

I don't really have a schematic (I drew it on paper and don't have a working scanner) and Multisim is on my laptop, so here's a quick bit of crap I did in Paint:
**broken link removed**