Hi everyone... thanks in advance for any tip or help.. my CPU is flashing yellow on the start up button.. I have disconnected yet nothing is working... any advice??
Thanks... :)

What make and model is your computer?

Dell demension E 510 desktop

On some Dells, the motherboard is fitted with a dodgy chip that 'explodes' randomly, have a look at this site;
Dell Dimension – Flashing orange power light at Random Fix - Computer Help (http://www.randomfix.com/2007/04/19/dell-dimension-%E2%80%93-flashing-orange-power-light/)

it has a good picture of what to look for.

If it's still under warranty, take it back to where you bought it!

Does the PC work at all? Did this just happen while you were on the PC or when you went away and came back and this was happening? Need more info to help you. Need to know what was happening before this started happening. Something has to cause this to happen, it just doesn't happen. More info if possible and we'll see what could possibly cause this.
Push the button and hold it in for 10 secs and see if that does anything happen?


Now, here is the owners manual for your computer, it is a .pdf file
Now when you open the PDF file the pages you are going to be interested in are pages 47,48 and 49 - they explain what the lights mean on you computer

http://support.dell.com/support/edocs/systems/dim5150/en/om/WD846A02.pdf

Once you get and idea of what the problem might be, post what is happening and we'll go from there - Hope this helps