rapid start was designed for use when SSD's were small (16-32GB was very expensive), and windows wouldn't fit on them. with a 120GB SSD it's not needed and would end up wasting a lot of the SSD as I believe that it would partition a 32Gb section off and the remainder would be inaccessible.
If you have built this system and you are receiving this message, follow this guide from Intel for setting it up prior to installing the IRST software.
rapid start was designed for use when SSD's were small (16-32GB was very expensive), and windows wouldn't fit on them. with a 120GB SSD it's not needed and would end up wasting a lot of the SSD as I believe that it would partition a 32Gb section off and the remainder would be inaccessible.