Is the SanDisk flash drive also USB 3.0 or just the port on your MBP?
Also, you'd probably get more feedback posting your question in the Mac Book Pro and/or Mountain Lion forums. This is the Snow Leopard forum.
And you could also take a look at this link: https://discussions.apple.com/thread/4113791?start=15&tstart=0. It would appear you might not be alone.