Make sure you have the latest OS and browser; make sure you clear out all the cache (Temp files etc.) from your OS and all history, cookies etc. from your browser.
Try another browser as if you are using anything but the latest version of Safari its compatibility with many sites is poor.
If it’s an Intel MAC you could also use dual boot and try a different OS to see if this solves the problem. (There are many Linux distros out there as well as Windows)
Bill
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English Riviera:
Live entertainment, Real Ale, Great Scenery, Great Beaches, why would anyone want to live anywhere else (I�m definitely staying put).