mahar116,

Click the link below to download the Intel Chipset Drivers for your computer. Reboot the computer and uninstall the network drivers and then reinstall them into the computer.

Dell Optiplex 780 Drivers, Downloads and Manuals

Thanks for help. I first uninstall the 3 gigabite network driver than i install latest intel chip set utility and reboot PC than windows detect it self network drivers and problem not solved solved.

You have winsock malware.

I reinstall the windows and all its drivers fotmate all the harddisk but problem of yellow sign present.I use the tools to remove malware but all in vain.

I solved my problem by seeing the video on youtube i use second option my problem solved.

link is under

https://www.youtube.com/watch?v=axVK8skvwtY

Thanks for your help guys