#$&* course Phy 201 I cannot open any of the PHEt files listed under lab/activity. My mac won't allow me to open it and the windows computer requires me to buy a $30 program. Do I need to purchase that program? When opening the file on the mac I get a screen full of symbols and numbers.When opening the file on windows I get a notice that windows cannot open the file and needs a program to run the file. It allows me to search the web for the correct program, but the two programs that will open the file are $30.