I tried opening a .aspx page the other day using the html editor in code view and it wouldn't show any code?

Is there a reason why I couldn't edit .aspx pages using the html editor?

Tools > Preferences > Files

In one of the first three lines (whichever is suitable) put this at the end of the line

Click OK at the bottom then restart CC HTML

If you double click the .aspx file that needs editing in Explorer you may have to set the file association to Coffee Cup but if you set it for 'always use this' then it should open in CC everytime after that.