bojadada 0 Light Poster

ok i got my 360 hooked up to my pc which is connected to my router wirelessly. i enabled ICS and i did all the correct settings and i can pass the test, but i lag really really badly on xbl. a few days ago the first time i got this working, i didnt lag at all. i dont understand why its doing this. and now whenever i connect my 360 to my pc and sign in to xbl, the internet on my pc completely stops working. but once i turn my xbox off it goes back to normal. it never did this before so i dont understand why this is happening. and before this starting happening, when i just lagged, my connection on my computer was perfect. all websites loaded instantly, i got a "very good" connection strength, and my dl speed is 3089 kb/s and my upload speed is 801 kb/s. its still really good on my computer, but whenever i connect my xbox to my pc, my internet completely stops working. could someone please help me? any help will be GREATLY appreciated.