Just for a test. You might want to plug in your moniter to onboard graphics and tell bios to run mother board on board graphic chip. You can always change back later.

Some of what I read with the research on the blinking cursor said that it had to do with a drive problem & somewhere it said that it could be a conflict among multiple drives. One thing to look at is to look to see if the sata drive is connected in the first sata port. Check your manual to find out which one that is. You could also check to see if there is an option to disable the other ports. On mine they are grouped into either 1 & 2 or 3 & 4 and I can disable either group.

Battery going dead after 2 years? One way to check that is to go into the bios and make sure that the date/time is correct & adjust accordingly. Then turn of the computer for a while and check the date/time again. If it has changed then it is surely bad. Another option is to to into BIOS and revert the settings to manufacturer's defaults. Until you get this figured out only change what is necessary which would at least be the boot order. What ever you do only make one change at a time.

I agree that we can almost rule out hardware or windows since you don't get any errors or have it crash and the hard drive tests passed but correct me if I'm wrong. Did memtest pass? Do you get any beeps? You should get one short beep. If you get more it is a diagnostic code that in a pattern of long and short beeps. We need to know what the pattern is.

First of all thanks for staying with me while I wrestle with this problem.

townsbg - There are no beeps at all when the problem occurs. If I hear those beeps I know its going to boot. I tried using just one drive, each one in turn actually. I reach a point where I seem to have isolated the problem a bad drive for example then I restart and the same problem occurs which means I am back to square one. But please read on as I want to answer rokytnji.

rokytnji - Its interesting what you say about the cmos battery perhaps that would explain why it won't even beep.

Anyway to bring you guys up to date. After running the tests I removed everything, the three drives, the PCI cards. Installed one drive it worked, installed the second it worked, installed the third it worked. Next I installed the graphics card it worked, so far looking good.

Then I installed my sound card and there it is no start up! I took it out again and it started ok. Next I tried putting the sound card into a different PCI slot again it wouldn't start. As I type this I am of the opinon that my sound card has died. If that is the case then I am gutted (hope you understand that it means I am rather disappointed) as it was quite a good one, the original Sound blaster Audigy Platinum but if the system continues to work without the problem recurring then at least I have found the culprit.

I will let you know how I get on and thanks again.
Llewitha

That sounds (no pun intended ) awfully suspicious. However please take out the card & check for Blown, Burst, and Leaking Capacitors. There is no need to read the article (although you can if you want); just study and compare the pictures. If you have any that is a sure sign that it is gone. I lost a graphics card to a couple of burst capacitors. Good detective work.

Thanks for the reply I will study the pictures and I will probably read the article.

At the moment I'm running with on board graphics and on board sound. It starts up without any problems but (any I've got a suspicion that this is quite a big but) if I plug in a usb flash drive and then attempt to do something - just moving the cursor as I go to begin something the machine shuts down.

I think that I had better study the motherboard capacitors as well as the sound card, what do you think?

Thanks
Llewitha

I think that I had better study the motherboard capacitors as well as the sound card, what do you think?

That won't hurt. Why aren't you using your graphics card?

I thought that I would run it in as bear a condition as possible for a while just to be sure it was ok. But then as I sad I plugged in the flash drive and it switched itself off. I tried a few times since and the same thing happens each time I put the flash drive in. Btw I have tried putting it into different ports.

I've had a good look at the capacitors on the sound card and I can't see any sign of a problem. But one capacitor on the motherboard looks to be bulging out on the top. I have no idea what that particular capacitor does but it is situated between the main power socket on the board and the cpu fan.

Llewitha

Bulging capacitors are never a good sign on a mother board. Unless you have a very good friend who is a hardware wizard who can solder you a new one to replace defective capacitor. You may be looking to save up for a new Desktop. A mother board replacement might be a option if you can find a match for the old one. I am not a hardware expert per se like Digerati. He would also suggest saving up for a New Desktop.

Sorry I can't be of more help to you.

Yeh that is a very bad sign. If it goes you might or might not be able to use you computer again. If you get the chance I would back up everything & keep it backed up.

I've backed up everything and I've done a reinstall of XP. I'm running a very basic set up but and it will run all day until I connect anything to a USB port. Once I've done that it shuts down by itself. Its as if it detects something and shuts down to protect itself.

It looks like I'm going to have to accept that its on its way out.

Thank you both for your help anyway.

Llewitha