How to delete Internat gateway??? and How to get rid of other PC's keyboard strokes ?

I use cable net. It identifies PCs on the basis of their MAC address. I have MAC address of another computer which is on the same LAN as my PC is. I installed a key logger on my PC as well. Now the problem is that some days before I changed my PC檚 MAC address to that other PC檚 MAC address. Now I have again changed the MAC address to original (which is actually mine). Now I don檛 know how my PC gets other PC檚 keyboard strokes. If I run notepad then I can see each and every letter that is typed by their keyboard. One other thing is this that sometimes I see another icon in my 楳y Network Places檚?properties which is in the internet gateway category. I never did settings of this gateway and it is not there for most of times. But why is it here?? And how can I delete it?? And how can get rid of that keyboard strokes problem??? Please help me?.... One more thing now i have uninstalled keylogger but problem persists :(How to delete Internat gateway??? and How to get rid of other PC's keyboard strokes ?
If your doing away with this stuff, go to add and remove programs in your control panel