Not saving as .sti files

IT reimaged my computer and now i am having trouble with my saved stickies.  It says that it is saving as a STI file but they will not open correctly. 
See examples



But the files look like this after saving 




In order to reopen the file I have to go through the process of choosing the app every time. If I choose open - it will open the installation file

Do you have the association for sti enabled in settings ? Some ( long ) time ago a user said he had to disable and enable again to make it work but i guess it was on winxp and an older stickies version but it is worth to try it