Kernel Panic Error When Using Pi as a Computer

[lenegene]

Hello,

I have just flashed my 64 GB SD card with the June 2017 RFD image and am trying to use the Pi as a computer to expand the card.

I plugged in the HDMI, keyboard, and mouse into the Pi and powered on the monitor. I powered the pi via micro usb using a portable battery charger, and I get the following error:


Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(179,2)


I have already reflashed the SD card to see if that would help, but no dice. I read online that you can hold the 'Shift' key upon start up? That didn't result in anything for me. 

Anyone know what's going on? 

Thanks

[lenegene]

Issue resolved: We moved the Lock Switch on our SD card reader to the 'unlocked' position so the card is read/write instead of read-only.