PTC always changes icons too, and one that causes me issues anyway, is the "close window" icon.
There use to be a red X in it, and not it looks too much like other file icons.
The workaround is to create your own mapkey to fix it as PTC does not allow you to edit system icons.
PLEASE put the red X back in the close window icon. This makes it very easy to see and understand what it is for.