hootch732

Hi all, my first post so please be kind. I installed an extra usb card into my desktop today and when I switched the pc back on it started to boot and then powered down and then started to boot and powered down again and so on. I removed the usb card and tried again with the same result in powering up and down. Tried the original power supply again and now nothing, help please! The spec is, as far as I am aware: MS7091 Motherboard 3Gb Processor 1Gb RAM Win XP SP3 1Gb Graphics Card Thank you.