Sorry to state the obvious, but you are double-clicking right? If you simply use the finder, can you open and see folders within your various drives? If so, try trashing FCP prefs and repairing permissions. If not, your OS might be corrupt (but try repairing permissions before doing anything radical). Also, it never hurts to run Disk Warrior.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 2 (FCP 6.0.5, Comp 3.0.5, DVDSP 4.2.1, Color 1.0.3)
Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN