What a helpful thing to say... wow where have you been all my life..
Actually, that's perfectly valid feedback in most cases--a bit on the "no duh/Captain Obvious" side, but still. It's amazing how many problems get resolved by a simple reboot.
However, UNSCSpartan3, this isn't one of those cases, so I can see why Mulreay responded this way.
But back to the problem, can you explain the steps taken and what router you are using what speed of connection and what you use e.g cable, Broadband. What are you connecting the Xbox to the computer with? More info please... full system specs, connection cables between computers, internet connection.
More info the better. 
welcome to computer hope
This/9000.
rjn15's question is pretty darn ambiguous--the only thing I can assume is that he/she wants to use Internet Connection Sharing to do one of these numbers:
1) Cable/DSL/whatever modem -> patch cable -> Laptop's Ethernet jack -> laptop -> built-in wireless NIC -> XBox 360's wireless adapter
or
2) Modem ---> wireless router ---> laptop's wireless NIC -> laptop -> laptop's Ethernet jack ->
CROSSOVER cable -> XBox 360's Ethernet jack
...and that his/her laptop is freezing upon these attempts.
In any case, rjn15, #1 and #2 are a waste unless you're using some kind of cellular modem (i.e.: a USB card from Sprint, Verizon, AT&T, or other cellular phone service provider). If not, then this is just making it more difficult than it should be. Barring the use of a cellular modem, these are what you want:
3) Modem ----> wireless router ----> XBox 360's wireless adapter
or
4) Modem ----> wireless router ----> one of the numbered ports on the wireless router (1, 2, 3, or 4) -> patch cable -> XBox 360's Ethernet jack
I can understand #4 not being an option if the router is nowhere near the 360. In that case, you're going to have to go with #3 and shell out some case for a 360 wireless adapter if you don't have one already.
