clutchc :
I presume you mean if you remove the Sandisk SSD from the system, you get the error message. Obviously if you remove the HDD from the system, you'll get the error message.
Did you install Win (7?) to the HDD before you installed the Sandisk SSD? I have uninstalled my 32GB Sandisk Readycache drive numerous times from various builds I've worked on with no issues.
Thanks for replying, turns out it was a faulty bootloader on the HDD, but somehow there was a good one on the cache drive... I don't know either but it's all sorted now, just created a windows recovery USB, took out the SSD and booted from the USB, ran startup repair, and all is well
Also, I'm using Windows 8.1, and even though my HDD was the 1st drive in the boot priority list (with the SSD not even specified on the list) the PC would still boot from the SSD