Hi Chris Welcome to this friendly forum. Photoshop CS4 may not be compatible with modern OS – try trashing the preferences to see if that resolves the issue. You'd probably be better subscribing to the Photography Plan which includes the latest version of Photoshop (currently 23.x.x) and updates as they become available plus Lightroom and some cloud storage for around $10 a month. There are lots of new features since CS4 and Photoshop would work well on your brand new computer. By @Derek Cross That would be grand - but, now I am no longer earning anything from graphics work - and existing on a pension, I cannot justify the recurring £120 per year this would cost.  My old, tried and trusted CS4 did all I now require.  I find this continual drain on my budget unacceptable.  I can save up and spend a reasonable amount on good software if I know that this is an end to my commitment but I cannot lock myself in to ever-recurring costs. ... View more

What you can try to disable the option to "Use Graphics Procesor" from Photoshop by going to Preferences, then Performance. Once done, quit & relaunch Photoshop to check if that helps. By @AxelMatt That works!  Thanks! Now to work out how to install an old enough Camera Raw plug-in.  Having retired from "heavy duty" graphics work, I would find it hard to justify a lot of expense...   ... View more