Try deleting the preferences, and other maintenance measures, like clearing caches.
Also, try running FCP X from another user account. I bet that FCP X will run smoothly in a fresh account, indicating that the cause lies somewhere in your user settings, preferences, or whatnot.
The 10.0.4 is the fastest and most stable version yet for the vast majority of users. I hope you soon see your problems resolved.
Also, Luis, I found if i make the blade cuts on the section of clip I want to take out, and immediately delete the segment, this helps correct the problem as well.
Hopefully, this is only aminor bug and will be fixed in the new 10.0.5 updaye (if there is one???).
Thank you for your help! I am much obliged!