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Then on finder, Hold down Option key on your Keyboard, click on Go menu and select Library. This will take you to the Library folder of your User Account. Open Preferences folder.
Trash the Final Cut Pro User Data folder. Trash the com.apple.FinalCutPro.plist file also. Then goto Applications > Utilities folder and open Disk Utility. In Disk Utility, select your hard disk Macintosh HD. Click Verify Disk and then Repair Disk. Click Repair Permission
Try FCP now. Please let me know if that didn't work, so we can continue troubleshooting. Don't Rate my answer until you are satisfied
Verify disk has shown that there are some minor repairs to be done.
It said that I should restart holding down the cmd and R keys. Just trying this
Repairs concluded successfully
FCP appears to be working for the moment...but the problems generally re-emerge after about 30 minutes or so.
I took a little time over this because I want to see whether or not it had regained its stability. It certainly seems to be fine for the moment from the latest editing I have carried out.
Interestingly I went through the same procedure as you suggested with the exception of trashing the whole folder and running disk utilities.
Thanks for your help.