URGENT copying, pasting and deleting tables

URGENT copying, pasting and deleting tables

Have created a table, copied and pasted it once. Second time it messes up the pasted table and impossible to delete it fully again. First table did not delete at all, then all visible parts were gone, but table area still there as blank. Can't delete it.
Am working on MacBook Pro, OS X 10.6.2, Firefox 3.5.8, Java enabled

Need to have the doc ready by this evening. Please help/assist.

THANKS!

Gregor