I don't now how you're removing your read-only flags, so try this:

1) Right-Click on the folder "Larian Studios".

2) Click "Properties"

3) If the read-only flag is grey, click twice; if it's black/white, click once. Make sure the read-only flag is empty.

4) Click Ok.

5) Repeat steps 1 and 2 and confirm that this indeed took effect.

If this doesn't work, run scandisk to make sure your hard drive doesn't have any errors preventing you from making some file alterations. Also, is your profile the administrator account on the computer? Are you the only user of that particular computer?