Sounds like a problem with the Horizonal Sync values. Be carefull with these values, as wrong values, can damage the monitor. I would go check the Sun site and check those values again..
Oh!! and also check to see what the actual screen resolutions that it will support. I sort of skipped over the fact that it's a Widescreen Monitor, so the aspect ratios will be different to a normal monitor. Which I guess means it will use none standard resolutions... (Similar to the Sony Vaio which did that too. Instead of 1024x768, it was 1024x576 or something to that effect. To give the Widescreen effect...)