Office Timeline requires Office (PowerPoint) 2007 have the latest service pack installed, Microsoft Office 2007 Service Pack 3. Without Service Pack 3 some installations may fail or the Office Timeline ribbon may not appear properly in PowerPoint.
Here are steps to check what Service Pack version of Microsoft Office 2007 you have installed: http://support.microsoft.com/kb/928116/
Close any programs you are running including PowerPoint.
Navigate to Control Panel and Programs and uninstall Office Timeline. Start > Control Panel > Programs > Office Timeline > Uninstall
Download the 2007 Microsoft Office Suite Service Pack 3 (SP3) .exe file by clicking on the Download button at the top of the page http://www.microsoft.com/en-us/download/details.aspx?id=27838
Save the file to your hard disk drive.
In Windows Explorer, double-click the .exe file that you saved to your hard disk drive, and follow the instructions on the screen.
Once complete re-launch PowerPoint.