Wont power on with HD power lead connected


I'm currently experiencing a new problem with my PC. It's a P4 3.4Ghz,
Gforce 6200 with DVD writer and 2x250Gb SATA drives. Yesterday, I took
out the DVD drive and now the machine wont power on. If I connect the
power, it attempts to power on twice, then gives up after about 2
seconds. If I disconnect the hard drive power leads, all if fine. The
problem occurs when either hard drive power lead is connected. I've
tested on a non SATA drive and it performed it's POST. Has anyone got
any suggestions?