This is soo annoying! please help!

[Toeclicker]

For a long while now when i go to put my car into reverse (its a manual by the way) its catches the gears. I thought that maybe the first few times i didnt have the clutch in all the way but now i make absoutely sure i have it in all the way and cant go any further, yet it still does it. Its not just reverse either but its much more common in reverse. Id say it does it at least once a day. If anybody could please give me any kind of input it would be greatly appreciated.
I also have one more little question...It seems that whenever I go full throttle I get knock at around 3000 rpms, I didnt think too much of it at first but it seems to never fail. Anytime I am full throttle and at or close to 3000 i knock. I think it has to be false knock but i dont know where to start to look for it. So any input again would be great thanks!!!