Well it works on my computer at home----

There are many reasons why a PowerPoint presentation might not work on any given machine. We believe that it is often due to some difference in the version of PowerPoint it was created in, and the version on the machine on which it is to be presented. PowerPoint is PowerPoint you might argue, but it's not quite that straightforward. Could you name exactly which version of PowerPoint you have on your home PC/laptop? Which Operating System? Which Service pack? Maybe the answer is yes, but could you then answer the same questions about the computer in the Lecture Theatre you have been allocated ( At March 2006 you could reasonably hope to find Windows XP Pro version 5.1 SP2. and Ofiice PowerPoint 2003 SP1. ) Unless your presentation was created and maintained using exactly that set up you might have problems. The table below illustrates some of the versions of PowerPoint available - you might have created your presentation a few years ago using PowerPoint 98, then changed a few slides last year using PowerPoint 2000, and now you're trying to run it on PowerPoint 2003. Plenty of scope for problems to occur - and if there's a Mac in the equation, think again!
If you have (e.g) movies in your presentation they might not work even if the PowerPoint versions are identical - So remember the golden rule that you must always try your file on the actual machine you are going to use for your presentation.

The table below illustrates some of the varioius PowerPoint Versions
Office version
PowerPoint 4
Office 4
Win 3.x, Win95, Mac
PowerPoint 95 (PowerPoint 7)
Office 95
Win95 or higher; no comparable Mac version
PowerPoint 97 (PowerPoint 8)
Office 97
Win95 or higher; comparable to PowerPoint 98/Mac
PowerPoint 98
Office 98/Mac
Mac; comparable to PowerPoint 97/Windows
PowerPoint 2000 (PowerPoint 9)
Office 2000
Win95 or higher; no comparable Mac version
PowerPoint 2001
Office 2001/Mac
Macintosh; halfway in between 2000 and 2002 Windows versions. Maybe that's why they called it 2001?
PowerPoint 2002 (PowerPoint 10)
Office XP
Win98 and higher; comparable to PowerPoint 2001/Mac
PowerPoint 2003 (PowerPoint 11)
Office 2003
TBD; generally comparable to PowerPoint 2001/Mac
PowerPoint X
Office X
Macintosh OS X
PowerPoint 2004
Office 2004
Macintosh OS X
PowerPoint 2007 Office 2007 Vista
Original table by PPtools As is the text below:
Generally, every version of PowerPoint can read and save files in the format of previous versions of PowerPoint. Since older versions don't support some of the features of newer versions, backward compatibility isn't complete.

Moving a presentation back and forth repeatedly between versions and/or between PC and Mac versions of PowerPoint will make your hair fall out. Small children will run away from you. Dogs will growl at you. And the world will generally not be your oyster. So don't.