"I am facing a very strange problem. I changed the program associated to a macromedia flash file to Notepad (right click -> properties -> open with -> Notepad) It somehow screwed everything up. Now all applications open on Notepad. Even when I click Internet explorer, a Notepad window opens, nothing works any more. I try to open System Restore and a Notepad window opens. Here is a screenshot."
Using the Open-with option for executables is not really needed. The accidental changes that you've made is revertable by altering the registry. I've written a tutorial here which explains how to overcome this problem.
.EXE files always open with Notepad or any other application ?
I hope this helps.