I had/have the same issue,
It is not clear why this happens, couldn't find any Microsoft blog post or something that confirms this, BUT, when looking through the Word 2010 settings I have found that there was a complete revamp of the shortcuts.
To "restore" word to the way you remember, you need to go to, File->Options->Customize Ribbon
On the bottom there is a label "Keyboard Shortcuts" and a button "Customize..." - click it
On the Categories box, scroll until you find "All Commands" and select it.
Now, from the right box select the following Command: EditCopy
Look at the "Current Keys" Box you will see "Ctrl+Insert" which is the NEW mapping
now put your cursor in the "Press new shortcut key" and Press Ctrl+C, a button on the bottom named Assign will light up, and you click on it.
Do the same for all the shortcuts you like, such as EditPaste, EditUndo, EditRedo, EditCut, SelectAll etc, then save.
Now everything works perfectly.
Again, I'm not clear why this wasn't communicated by MS, it seems they are trying to force a new (old) standard on us that was used in mac for a long time,