Was looking at a Koni Cup 996 C2... The car had an ABS reset switch on the dash.
What problems did these cars have when raced which required this reset switch?
My first thought was "ice mode" but I'm thinking that goes away quicker than you could find the switch.

 

Mine does not have an ABS reset switch and I have not experienced any issues.

 

I had a 996 with ABS switch. It was labeled ON/OFF. explained reason, sometimes better in the rain. I never switched it off

 

More likely sensitivity to triggering a wheel speed sensor fault on rumble strips...