Internal Storage doesn't get mounted
Sounds like it might be your ROM. You could start by clearing the cache and dalvik. If it were me, I'd back up my sms and mms and do a full flash. I doubt a factory reset alone will help. I had an issue with permissions when my phone was connected to USB with certain ROMS, sometimes accessing with my PC, sometimes through recovery. I have to believe it's ROM related since the current version of PAC-man I'm using has been much more cooperative. I doubt it's driver related, but that'd be the safest starting point if you have sensitive data on your phone.