excel 2007 files cant open when double click

this is a strange problem, when you double click previously saved excel files nothing happens, but you start start excel 2007 program from start menu, then try to open the saved files using file > open files can open, to fix this problem follow these steps.

• open excel 2007 (using start menu)
• go to tools > options > general. uncheck "ignore other apps"
• now close excel program
• now click start > run then type excel.exe /unregserver and click to unregister excel
• then again click start > run type excel.exe /regserver and click to re-register excel
• now double click saved excel files, it should work normally