If you get this freeze when using a graphical login manager (xdm, gdm, kdm), 
attached patch from xfree86 bugzilla [1] fixed this problem for me (Radeon 
Mobility 9000).

[1] http://bugs.xfree86.org/cgi-bin/bugzilla/show_bug.cgi?id=94

BR, Sami
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Linux 2.5.67-bk4