Use Calibre to manage your Library . There is a tickbox option to replace spaces with Underscores (when transfering).
That only applies to transfers made after the setting change.
Get your USB connection issues resolved to rock solid operation
You will trash
the file system on your PEz so long as long as you have problems. They only question, is when it WILL it happen
Stay away from the front USB connections, they are hub extensions (not direct) on some systems.
I put a D-Link DSB-500 (USB1.x) card (about $10 at Fry's) in my Dell.
The 8 built in ports (Intel) all failed with the PEz with "Enhanced USB2.0" enabled. Now I have both speeds available.