Dell laptop charger no longer fully recognised

Hello, turning to you guys for help once again.

I have had a nice Dell laptop for just over a year now. It was bought in the states while I was over there last year and not by me so no warranty I believe.

Now it has a common problem (apparently) where the original official Dell charger is no longer properly detected by the laptop. This leads to a startup BIOS message warning of decreased performance (!) and the battery no longer being charged. Same message in windows when plugging in the charger.

Quite annoying my one year old laptop now can't charge it's own battery :( I see a couple of possible options, one is to get a new (Dell or copy) charger cheap. Where should I look to get one cheap? Second hand would be fine too.
If it's a copy it will presumably come with some Bios hack to enable battery charging again and full performance etc.

Second cheaper option is just to somehow just do the bios hack myself and make the battery charge with this undetected charger. I'm thinking if I can get hold of a CD which comes with a knock off charger and use it to update my bios this might work? Anyone have one of these things?

Finally, I'm not sure of my laptop's exact model (this will matter for the bios hack) I will check when I get home later. And apparently this is caused by no EMI shielding on the electronics which ID the charger in the charger and the laptop. Sometimes the fix is change the charger, but sometimes a mobo swap is needed. Lame!