Problems Office 2007 “Not registered message”

Hi guys,
I have a Dell laptop. It is really a good system with many installed features. I have Office 2007 installed in it.
Last night my friend sent me lectures in PowerPoint presentation.
Whenever I try to open the presentation, the following error message is displayed:

Microsoft Office PowerPoint
Some controls on this presentation can't be activated. They might not be registered on this computer.
I even tried to search this issue online but am unable to counter the situation.
Any help would be appreciated!
Thanks.
