DVD Drive E: Drive disappearing from Vista Home Premium 64

I have two SATA Liteon DVD drives, E: DVDRW LH-20A1L and F: DVD SHD-16S1S. Starting yesterday,Drive E: disappeared from My Computer and is not displayed in Device Manager, BIOS shows it's there. Yesterday Vista started taking longer to load too, the green loading bar freezes for about a minute. I tried running Start Up Repair from Vista Disc, repair didn't fing anything so I used Restore Point. Still the same problem. PC is about two years old, I built it, with Vista and MOBO drivers/downloads up to date. I'm not getting any error codes as similar posts state. Drive F: has no problems loading. Drive E: has latest Firmware too from Liteon. Until yesterday Drive E: had always loaded. At a loss as to why Vista can't see it when Bios does. Both drives have power as the led lights blink at start up and i can open E: by pressing button. Any direction in solving this issue would be appreciated...thx!