Thread: Internet connectivity lost while accessing networked PC

well sorry for the ambiguous thread title, posting in a hurry.
So here goes the problem:

1. Broadband connection is Airtel 1299/- plan 512 day/ 1mbps night unlimited.
2.Router or modem whatever is connected to a 8 port dlink switch.
3. Five computer's are connected to the switch.

one pc is for download purposes and runs 24x7. Now the real problem is whenever i try to access the download pc then my pc looses internet connectivity. ill have to remove the lan wire and reinsert it or disable/enable my lan adapter to make it work again. see the below screenshots :
one is while accessing internet and the other is while transferring data between pc's