I replaced the power supply in my Dimension 9100 today. Took out the old one and connected everything to the new one. Everything worked perfectly.

I then tidied the cables screwed everything shut again etc and now when I switch on the PC the fans all start, the LEDs come on, the disks and DVDs etc make the usual startup noises but all I get on screen is a flashing cursor in the top left corner of the screen. I don't get any beeps and the BIOS screen isn't displayed.

I assumed I must have knocked something loose when shutting the case back up so I opened it up and made sure everything was still connected and firmly seated but it hasn't made any difference.

Please help!

Never mind, panic over. Took the machine apart and put it together again and it's working now. Must've accidentally loosened something.