QUOTE(jonnythejackass @ Jul 5 2006, 08:39 AM)

yh the game is on my harddrive but when i load it stops at 3/4 on the loading bar

I've had this happen before and I've been trying to remember the things needed to fix it.
Here's some things to try/look out for:
Make backup copies of files being edited BEFORE editing them. If a lockup occurs, put the backed up file back in place.
Clear any cached files off of X, Y, and Z and reboot if lockups occur.
Check the ini files for the name of the last player profile you used before it locked up. Delete (and create a new ) or rename the profile. Sometimes changes to the settings can confuse the game when it tries to resolve the player profile.
Make sure you do not shut off, or restart, your xbox until you are back at the game's main menu. I think the game writes some things back to the ini files or the user's profile when you go back to the menu. So, always go back to the main menu before bailing out of Rainbow Six games.
You might try making the user.ini file smaller. It's a hypothesis of mine that the user.ini file cannot be much larger that 10kB, but I have not fully tested this.