Xfree86 taking up 99% of cpu and hanging system

[Mitchell Laks <mlaks@verizon.net>]

Hi,
suddenly  I have my debian sid system/ running KDE freezing 
 and 
when i ssh from another system  and when I run top
i see

7063 root      25   0     0    0    0 R 99.8  0.0  14:33.81 XFree86
1 root      16   0  1500  484 1344 S  0.0  0.0   0:00.57 init

so XFree86 is full use of cpu.

I then run kill -9 7063 as root and then contrinue to monitor top i still see 
it persist

and then i kill a number of other processes and still
 7063 root      25   0     0    0    0 R 99.8  0.0  21:26.62 XFree86
    1 root      16   0  1500  484 1344 S  0.0  0.0   0:00.57 init
    2 root      RT   0     0    0    0 S  0.0  0.0   0:00.09 migration/0
    3 root      34  19     0    0    0 S  0.0  0.0   0:00.03 ksoftirqd/0

and then  the system still doesnt respond. i try ctl-alt F2 to get a console 
and no improvement.

I finally have to shutdown -r now to get my machine back.

how can i diagnose what is causing the problem and how to use my login via ssh 
and restore system without shutdown -r noww?

thanks,
Mitchell