I've had Win7 installed on my 2.5" SSD for a few months. The computer also has a mSATA slot which I've now packed with a 16GB SSD. I've installed Ubuntu onto the mSATA disk from USB which went fine without any errors.
Now to the odd bit; when I boot to the mSATA with Ubuntu with the Win7 SSD connected, GRUB doesn't load and I'm stuck at a blank screen (I've changed the GRUB.cfg timeout to five, and set nomodeset and tried forcing VESA which still gives me blank, which is why I think GRUB's at fault, not Ubuntu). But if I unplug the Win7 SSD, everything works smooth and fine booting to Ubuntu via GRUB.
Both Ubuntu and Win7 are in Legacy and my motherboard is set to Legacy support. Motherboard's port as mSATA=Port0 and the SSD SATA=Port1.
Any help would be great, thanks.