.exe opening file errors

Hello,

I have a sony vaio with windows 7 and I recently opened a .exe file by choosing a default program (google chrome) in the windows startup menu. I also clicked the "always use the selected program to open this kind of file" button, and when I did this basically every program on my computer is using google chrome instead of the correct one. For example, I clicked on the itunes button on my desktop and google chrome popped up. This happens for all my desktop programs. I am nearly 100 percent sure this is not a virus, but rather a wrong button was clicked at some point. I tried regedit in the start menu but it failed to work so if anyone can help me that would be great!

Thanks!



<config>Windows 7