K7S5A problem changing clock speed with speedfan

I want to use the adaptive clock speed feature of speedfan "Automatic clock
control feature" but every time that I change the system clock using
speedfan, the computer freezes!

Basically, I want to be able to underclock the system when I am not using it
much. I would like to force the system to go at the setting: CPU 66,7 PCI
33,3 and SDRAM 66.7 that would run a 766.7 MHZ.
The system will run reliably at a slightly overclocked settings 1900+ and
2000+. I can choose these settings with the HoneyX bios and I used to
choose them with speedfan but it doesn't work anymore

Anybody had experience with the software clock control?

Charles Leblanc

Hardware:
K7S5A
Honey X bios
512MB SDRAM PC133
XP1800+

Software Win2K SP4
Speedfan 4.09
Clock defaulkted by Speedfan ICS 9248(ABC)F-199
The read clock feature works but the set clock doesn't work anymore.