GRACE Kelly coasts her way graciously and beautifully through High Society (World, 11.00am), but she does so like a woman whose mind is on other things. Perhaps it is not surprising. This was the last film she made before marrying Prince Ranier of Monaco and becoming Princess Grace, so perhaps she was thinking of what colour wallpaper she might like for the palace. In fact the thing that turns High Society from what should have been a fine film into a merely average one is the fact that all the principals act like a bunch of people who are already so famous that they don't have to try hard to be famous any more. Frank Sinatra is irritating and overly hip as a reporter sent to cover a big wedding and Bing Crosby is far too old for his role as one of Kelly's three suitors. He looks like a piece of walking beef jerky. High Society is a flat re-working of The Philadelphia Story with only a few bright moments, most of which are Cole Porter's songs, notably Well, Did You Evah? and Who Wants To Be A Millionaire? the answer to which is ''I do''. Satchmo (Louis Armstrong) makes a welcome appearance, white handkerchief and all. IN the world of enigmas, Roman Polanski is the most enigmatic of them all. Unconventional private life aside, his screen career has veered seemingly uncontrollably from the sublime (Chinatown, Tess) to the ridiculous (The Fearless Vampire Killers and most recently Bitter Moon, some of which was shown in Hong Kong recently; the rest of it consisted of grunting and groaning and was perhaps understandably left in the censor's rubbish bin). Which category Pirates (Pearl, 2.00pm) falls into is a matter of some debate. American critic Leonard Maltin said it has little plot, but is fun anyway. British critic John Walker said Polanski should never be allowed to do comedy and described Pirates as ''revolting when it is not a crashing bore''. What is in little doubt is that Pirates was sumptuously filmed and will lose much of its impact, if indeed you find it has any, on the small screen. Rotund British comedian Roy Kinnear has been cast afloat on the high seas and is picked up by a Spanish galleon populated by sailors awash with rats and unsocial diseases. Walter Matthau turns in an entertaining performance and there is a rousing score by Philippe Sarde. DANNY DeVito shows with The War of the Roses (World, 9.30pm) that he is sometimes a more entertaining director than he is an actor. Little in life is sadder and sillier than the break-up of a long-married couple and this fiendish film shows divorce inall its black tragedy. It is a rancorous saga and too mean-spirited to be hilariously funny, but what DeVito does manage to convey is what many of us have often suspected - that human beings are often very stupid creatures. Michael Douglas and Kathleen Turner are the once-happy pair whose marriage dissolves into bickering, silence, acrimony and then full-scale, no-prisoners war. IN the silly Spontaneous Combustion (Pearl, 12.50am) paranoia takes hold when people begin to spontaneously combust. But then it would. It is difficult to lead a normal kind of life, catching the tram, ambling happily through Park N' Shop, when there is a chance you will turn into a human bunsen burner without warning.