It sounds to me like the monitor is degaussing itself.  This system is inbuilt into most monitors to provide a means of de-magnetizing the coils surrounding the tube.  However, it usually only runs when you tell it to, and then for a few seconds at most.

If I were you I'd speak to the monitor supplier.

Ian Porter
Computer Guys Inc.
Arrowtown
New Zealand
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  ----- Original Message ----- 
  From: cfinnigan 
  To: [log in to unmask] 
  Sent: Monday, September 29, 2003 3:32 AM
  Subject: [PCBUILD] CRT problem


  i have a Mag innovision 19" monitor (9 mos old) that i have set to power
  down after 20 minutes in XP pro. starting yesterday, whenever i open a full
  screen program, OE, Word, IE, an inch at the top and bottom of the screen
  shook / wiggled horizontally, very quickly, lasting about a minute. it only
  shakes  with the program maximized, not the desktop. and it only lasts a
  minute. i have not installed or removed any new programs in weeks. the video
  card is an Nvidia Geoforce 2 MX/MX400 AGP. screen res is set to 1280 x 1024,
  highest (32) color quality, 75 refresh rate (set for months). any suggestion
  before i call within the warranty period would be welcomed.

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