Ok so as the title stated, if you downloaded the patch and your xbox is now fxors.. you can do this temporary fix. (It basically uninstalls all the patches/updates your system has downloaded and installed on the hard drive)
Clear your Xbox 360 hard drive's cache.
In the Xbox 360 dashboard, select "memory" in the system blade and highlight your Xbox 360 hard drive. Now press: Y, X, X, Left Bumper, Right Bumper, X, X. You should recieve a message that says, "This will perform maintenance on your Xbox 360 storage devices. Do you want to continue?" If you click yes, your Xbox 360 will clear it's hard drive cache. If you click no, you'll be returned back to your dashboard menu. This will help your Xbox 360 run a tad faster and fix freezing issues. Note that this will delete all downloaded content and updates, although your save games will remain.
After I did this I was able to play guitar hero 2 again for hours without it freezing/red lights of death as it had been doing. Now my Whammy bar isn't fully functional anymore, and I can't connect to xbox live while on GH2 because it isn't updated, but at least the game works!!
Sorry for a double post but I am going to put this into the GH2 game thread as well, I just figured I have seen enough posts all over the internet about this problem that I felt it deserved to be on the more viewed page.
Good Luck with the game (I have 7 more levels of expert to go and 2 more on hard)