Attention: Unsupported video configuration detected...

Yikes is right! I'm not a computer tekkie. I've tried restoring the load defaults to factory defaults,(F2) I've taken out the battery and then reinstalled but no success. I'm not clear about resetting the cmos - I've looked at the manual but I'm still confused. I've found the jumpers in the computer but don't know what to do with them! kinda need taking by the hand.....

No setting or wiring has changed, and it just started saying that?  I'm not sure there's going to be a stock answer for that--it's not supposed to happen.  So you're on onboard video, not a plugin accessory card?  And it mistakenly thinks you do have a display card when you don't?  Yikes!

 

Try resetting BIOS.  It seems badly confused.  The location of the jumper and procedure will be in the online manual.  If the reset brings the display back, you will have to F2 and reenter your configuration--what drives and plugin accessories you have. If it doesn't, I'm not sure what else to try.  Anyone?

I left Dell before the C521 came out, so I'm not firsthand familiar with it.  Taking out the battery for 3 minutes should have done it--assuming it was unplugged at the time.  The jumper does the same thing, only faster, about 30 seconds.

 

Not all Dells even have jumpers.  In some, they have elected to save a half cent and just put posts in.  I don't know what the 521 has.  The conventional jumper had 3 hollow posts.  The jumper is stored on two of them that aren't connected to anything.  The third one is the active one.  Moving the jumper to that one engaged the reset function.

 

If your motherboard thinks it has a video card installed when it doesn't, it may be, colloquially, toast. 

I took out the battery for only 30 seconds, I'll try it for three minutes and see what happens. You're right about the jumpers: there's just two posts. Here goes......

So took out battery for 3 minutes this time but no joy. Unlike the last time the time and date reset. Inside the computer there is the CMOS Reset (RTCRST) consisting of two posts. There is also the password jumper, again two posts but with a plastic cover (the jumper itself?) Is it possible to reset the CMOS, do I want to, and how do I do it? Getting desperate!

Nevermind the password jumper.  RTCRST is the one you want.  Connect the two posts with something metallic like a paperclip.  Or the plastic thingy if it has metal posts.  That's the half-cent Dell saved giving you only two posts and one plastic thingy.

 

Unfortunately, if you already took out the battery for 3 minutes, it's not likely to alter the result. If the motherboard thinks it has a video card when it doesn't, it has most likely failed.

 

Like I said, this is not supposed to happen, and I've never seen it happen in around 2000 systems I've looked at.  But the rule in computer diagnosis is that anything CAN happen, and the best you can do is go from where you find yourself. 

Thanks for your message Livecam. I've tried with a crt but I still get the same result. I can't even start the computer in safe mode to get around the message and uninstall! I press F8 during startup but there's no response. Any other way to start in safe mode?

It's not resolution.  The 'wrong port' message is from BIOS.  It's supposed to say that when you hook a monitor to onboard video, while at the same time having a video card.  If it says that when you DON'T have a video card, it's badly confused or just plain broke.

Having spent nearly 3 hours "chatting" with the support team they finally decided that it WAS a mother board problem. And those nice people from Dell are actually sending a technician all the way from Paris to replace it. So, assuming all goes well, normal service will be resumed tomorrow. Thanks to everyone who tried to help

 

Merci beaucoup

Jerome 

Great.  I didn't know it was in warranty.  It's definitely a hardware/warranty issue.

 

I can't explain why it took them 3 hours to figure it out, except that the people who answer the phone for Dell tend not to know what the smoof they're doing.  It took me about 15 seconds to figure it out, but I didn't want to jump to conclusions based on spotty evidence.  Then again, I would charge them $25 an hour to do what I do, and the people answering the phone get $3 an hour.  Ya get whatcha pay for.