I've done some further research in the docs and i'm afraid you won't be able to fix it on XP.
The default timeout is higher than Vista/7 (2 seconds), for XP it's 5 seconds,
but the keys won't work on it.
The only option is to add a 2nd GPU and use it for octane rendering,
and it has to be a GPU that is not connected to a display/used for displaying a windows desktop.
Individual GPU program launches are limited to a run time
of less than 5 seconds on a GPU with a display attached.
Exceeding this time limit usually causes a launch failure
reported through the CUDA driver or the CUDA runtime. GPUs
without a display attached are not subject to the 5 second
runtime restriction. For this reason it is recommended that
CUDA be run on a GPU that is NOT attached to a display and
does not have the Windows desktop extended onto it. In this
case, the system must contain at least one NVIDIA GPU that
serves as the primary graphics adapter.
since the FX1700 is quite a slow card, i would recommend for you to get a 2nd GPU, a GTX200 or GTX400 series.
you'll be able to use octane with far more complex scenes as it will have more memory,
and you'll have a much smoother experience.
Our 32bit system is running XP here, and it has 2 gpu's in it (2x FX3800, and when using the 2nd gpu, it works flawlessly)