Connection Dropping

Hi, can someone please help me?

I've been having problems with my broadband connection randomly dropping for a couple of months.

 

I've had the modem replaced by my ISP, numerous engineer calls to check the line, signals etc. , Dell have replaced my motherboard AND i've reformatted my hard drive.

 

I have a Dell Dimension 8300 and basically my connection randomly drops for a couple of minutes only to come back without me doing anything. While it's down, the modem lights are fine and the PC doesn't recognize the connection is lost until I reset my PC.

 

I really don't know what else to do now as my ISP have done all they can and say it must be a hardware problem.

 

Hopefully someone can help me.

 

Thanks.