It happened to me recently when I went to see Gypsy at the MGM Shaftesbury Avenue. Twenty minutes into the film the narrative took a sudden lurch forward.
At first I thought the reels had been played out of sequence but then it dawned on me that some footage had gone missing. And it had - a complete scene. (Six days later, I was told, the lost footage turned up. It had been sitting in its film can all along and nobody had bothered to look.)
Was I offered a refund, a chance to see the film again, a free bag of popcorn? No, I was not. The cineaste's charter is a long overdue piece of legislation.
Things are likely to get worse before they get better. With so-called 'improvements' in technology, a projectionist no longer needs to cue reels, but instead can switch on, take a 90-minute break, then return to switch off.
Multiplex cinemas can employ one projectionist to run between the various screens - with farcical consequences. Only last weekend, at a special children's day at UCI Whiteleys, the image was Jurassic Park, the soundtrack The Flintstones - I kid you not. And here we are paying upwards of pounds 7 for 'the cinema experience'.
Technology, however, isn't solely to blame. In the good old days of the Scala all-nighters, I once sat through a very trashy quintuple bill - isn't it always the last film in the programme you are most eager to see? In this case it was Russ Meyer's Beyond the Valley of the Dolls. So, at five in the morning the credits roll and - aargh] - on comes the very drab Valley of The Dolls. The cinema had ordered the wrong film. Well, it seemed a bit churlish to ask for my money back, as I'd already seen four others.
Even the most professional cinemas sometimes get it wrong. The National Film Theatre, when they last put on a season of John Wayne films, was screening a rare print of The Alamo. So rare, that an Italian gentleman had flown in especially.
However, at the last minute it was discovered that only four of the seven reels had turned up. To their credit, the NFT proceeded with the screening, delivering an impromptu commentary between reels to provide continuity. Such gestures are rare.
If cinemas are going to coax us away from our movie channels and videos then they're going to have to work a lot harder than that - and I'm not talking about free popcorn.