Wired Ethernet connection constantly dropping

I have an HP computer, with Windows 7 64-bit, about 4 days ago, my desktop's internet connection will continually drop out and come in ever 30 seconds or less. I have tried to reset my router and modem and it did not help. I have ran norton constantly and ran malawarbyte twice with full scan. My connection allows me to get online, but with the connection constantly dropping, i cant watch any videos because the connection will cut out and when online internet explorer will come up saying cannot display web page. Ive tried google chrome and media firefox and both have the same problem so i know its my connection and can see it dropping at the bottom right of my screen. My router is NVIDIA nForce 10/100 Mbps Ethernet. When i booted my computer up in safe mode and networking my connection was completely stable and worked great. Does anyone have any idea whats happening?

How old is your modum and have you reset? Have you called your ISP to see if it's on their end?

my modem is about 1 1/2 years old and provided by comcast, ive reset it and it did not help at all. All my other computers work fine on wireless the desktop is the only computer with a problem