Fatfox

Is the power button LED, solid green, blinking green, solid amber, blinking amber?

Check the reading of Diagnostic Lights on the front panel,

The 3100c Diagnostic Guide and Troubleshooter is Here:

http://ftp.dell.com/Manuals/all-products/esuprt_desktop/esuprt_dimension_desktops/dimension-3100c_Service%20Manual_en-us.pdf   

The following article with solutions may also be worth a read:

https://neosmart.net/wiki/error-loading-operating-system/
                                                                         
Bev.

Run full F12 diagnostics:

http://dellwindowsreinstallationguide.com/f12-preboot-diagnostics/

Then if all passes clean install Windows XP, follow the instructions here:

http://dellwindowsreinstallationguide.com/a-clean-install-of-windows/legacy-windows-xp-reinstallation-guide/

Thanks the power light is green and the four green lights all flash on and off during the fire up and all go out

I sometimes get the Dell screen and that enable me to get to the boot menu by pressing F12 - not sure if that helps?

No beeps - I did try boot from hard drive on the boot menu but got the same message.

i' ll see if I can find the diagnostics disc

poormansfoor

Have you run the Dell Diagnostics, as suggested, see page 4 of the service manual, the Dell resources CD that was shipped with the computer package can be used for this?

Are there any 'Beeps'?

Bev.

Found the diagnostics disc. The menu was slightly different from the one in the manual but have tried hard drive diagnostics and it says Drive 0 Pass press enter to reboot and Im back to error loading operating system. Does this mean the HDD is ok?

Fatfox

Try running the extended test on the hard drive.

'Error code 650F;137B IDE device failed. Blank media or no media present in optical drive', means there was no data disk in the optical drive for testing.

Bev.

Fatfox

No Beeps, or Diagnostic lights, can indicate a motherboard issue.

If you are comfortable working around computers, you could try the following:

Note: The only 100% method of testing a PSU, is to install a known working power supply.

Unplug the cord from the power supply, hold the power button in for about 15/20 seconds, open the case, unplug the 20-pin power connector from the motherboard and jump the Green wire to one of the Black wires, reconnect the power cord and power the system on, if power supply, case fans and the hard drive run, then the PSU may be good.

Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper.

Power supply checks out and the system still does not work, again remove the power cord, hold the power button in for several seconds to discharge the residue power, reconnect the 20-pin connector to the motherboard.

Remove all the PCI cards, the video card [if applicable], memory, all peripherals, disconnect the data and power cables to all the drives, check that the front panel cable is connected to motherboard, with nothing else connected to the system, reconnect the power cable and power the system on.

If there is no difference in the diagnostic lights, 'Beep' codes, then it would appear that the motherboard has died and/or maybe the processor.

Note: The good news is, processors rarely fail, as the only method I know of checking a processor, is to install it a compatible working PC, or use a known working processor.

Before working inside the case, always power the PC off, remove the power cord and hold the power button in for several seconds to discharge the residue power.
 
Bev.

Thanks shesageordie. I don't mind giving it a go but before this happened i had had a number of blue screens /physical memory dumps screens when first firing the machine on.

Turning it off and on again generally sorted the problem and once it was up and running to the Windows screen it was fine. Then about a week ago i got a blue screen after the machine had been on a while. This was the first time and it never recovered. 

Just wondered whether there were any clues there before I poke about inside?

Thanks

Thanks shesageordie. I don't mind giving it a go but before this happened i had had a number of blue screens /physical memory dumps screens when first firing the machine on. Turning it off and on again generally sorted the problem and once it was up and running to the Windows screen it was fine. Then about a week ago i got a blue screen after the machine had been on a while. This was the first time and it never recovered.  Just wondered whether there were any clues there before I poke about inside? Thanks