I have a computer that is running Windows XP with Office 2007 Professional. He is having problems only with the Powerpoint files in the office, specifically .pptx files. When you double-click on the file it opens up to a blank presentation. Once that is open if you click open and navigate to the file then it opens correctly.
I have checked the registry and the open/command path is correct. Any other ideas will help. All the others work fine Word, Excel and Outlook.

reinstalling the software again will definitely help. instead of taking all the burden just uninstall and reinstall the software it will work

Check your extension make sure it is right
For this incorrect file associations, Repair the pptx. You may have to restart your computer after the repair is completed.