I've deleted the FCP program preferences and verified the system and external hard drive disks. FCP usually runs smoothly for a solid hour or two, then it'll expectantly quit and continue to quite within minutes of startup thereafter. Perhaps I am not deleting the correct preferences? Under FCP User data there's the standard FCP 6.0 Prefs and FCP Prof Cache, which I deleted, then there's a sub folder called FCP 6 Rescue (I'm not sure if this is a program that was previously installed before I worked with this computer) that has FCP 6.0 Prefs, FCP Obj Cache, FCP Prof Cache then .com.apple.FinalCutPro.plist, should these be deleted as well? Would a program like Disk Warrior be helpful here?
I would copy your media files off the external drive to another drive, then re-import/re-link those into your project. If your external drive is dying, better to do this sooner than later. Consumer HDs have a high failure rate when used in video editing. Try running your disc utility program and see if anything shows up.