I would ask on an Adobe forum. But isn't Photoshop 5 very very old? According to Wikipedia, it is from 1998! I don't think it would work at all in High Sierra. Maybe you mean CS5? That's from 2010.
Either way, you should probably update. Or, if you don't want to update because of the cost, then at least look to switch to an app that fits your budget. I have a list of them right here: Mac Photoshop Alternatives. I've been using Acorn and Pixelmator a lot myself.
I would ask on an Adobe forum. But isn't Photoshop 5 very very old? According to Wikipedia, it is from 1998! I don't think it would work at all in High Sierra. Maybe you mean CS5? That's from 2010.
Either way, you should probably update. Or, if you don't want to update because of the cost, then at least look to switch to an app that fits your budget. I have a list of them right here: Mac Photoshop Alternatives. I've been using Acorn and Pixelmator a lot myself.