help with dll files

hey guys, a member of staff just tried to help me,, and im sorry

for all of these threads but he told me to make a thread (.....)

basically all of my crossfire DLL'S and all of dll's in general are opening with notepad

its not the official symbol for a dll its just a notepad document with .dll at the end

so all dlls have dll at the end

but by default is notepad, how can i make it back to the normal default program
of dll

look here is picture

never heard or seen this before