Troubleshoot Link and Hyperlink Problems: links break, hyperlinks break, go to wrong slide, sounds or movies don't play
Sounds that don't play, movies that don't move, links to other slides or files or web pages that just don't work ... chances are you'll find a solution to the problem in one or more of these PowerPoint FAQ pages:
Check to see if the link is applied to a transparent shape or a shape with no line and/or no fill. If so, give the shape a solid fill and make the fill 99% transparent instead of 100%.
Sounds/Movies don't play, images disappear or links break when I move or email a presentation
Lost hyperlinks, hyperlinks link to wrong place, hyperlinks stop working
Sometimes you can manually repair or re-target a link using this:
Show me the link and let me edit it
Note that links to files with hashmarks ( # characters ) in the filename will usually not work. This character is used for other purposes in URLs and in PowerPoint's internal hyperlink storage and confuses PowerPoint when it appears in filenames. Rename the linked files to remove the "#" character and re-create the hyperlink to solve the problem.
Problems with LINKED EXCEL CHARTS in PowerPoint
Hyperlinks don't work after copy/paste
Graphs don't update automatically
If your links work perfectly in PowerPoint but stop working after you convert the presentation to PDF, have a look here:
Bad hyperlinks in PDFs from Acrobat