If you mean 10.4.11, TenFourFox is compatible with 10.4.11 and
10.5.8. Just pick the right version for your processor.
If you mean 10.4._1_, you need to update your Mac. Run Software
Update to update your Mac to 10.4.11. TenFourFox will not run at
all on a version of Mac OS X prior to 10.4.9, and we do not support
users of 10.4.9 or 10.4.10 due to bugs fixed in 10.4.11.