Odd effects - connecting Zen Sleek Photo to audio amp using 3.5mm jack to RCA lead

[gdickin2]

Hi

Bit of advice please. I have recently got a Zen Sleek Photo (well my 2nd actually cos the 1st died after 48 hours - thank God for Argos returns policy !) and wanted to connect it to my home hifi amp for listening to at home. I bought a 3.5mm jack to RCA lead. The lead is plugged into the Aux in on my amp and the jack plugs into the headphone socket on top of the Zen.
However, every time I plug the lead into the Zen it reboots and then does one of, hangs, plays but the buttons don't respond, needs rebooting again - all fairly random.
If I plug the headphone lead into the socket on the Zen it doesn't do it.
Has anybody experienced this before, is there a workaround, am I damaging my Zen ?.

Cheers.