Hate to necro, but this is relevant.
I have an old IBM P275, got it back in '04 from a friend of mine who built and refurbished towers in his living room. It's the best monitor I've ever had, hands down.
Over the past year or so it has been doing the same thing Garnet mentioned. Can't say what it is for certain, but it is definitely related to warmup. I found that if I leave it on for most of the day, and only turn it off when I go to bed at night, it minimises the problem. Also, on the occasion that the screen loses focus, turning it off for a short bit (5-15 minutes) then back on usually fixes that.
It also has angled striations of discolouring on the occasion that it still happens, mostly a greenish tint, and sometimes when it pops I'll see a red flash, and then the screen takes on a decidedly bluish hue. I always assumed it was finally starting to go out. Maybe it is, maybe it isn't, but by gosh it's older than dirt so it wouldn't surprise me much if it were.
Fingers crossed - you'll be hard-pressed to find a good LCD monitor that even comes close to the res capability of this monster. It's a shame they're so hard to find these days... when mine finally goes, I'm shelling out whatever it takes to get another one. Hope this helps some other fortunate P275 owner.