BINGO!
I had this exact problem some 12 months ago and after a helluva lot of fluffing around trying different things I ended up getting NEC to send out a technician to my studio to update the firmware in my 2690 Wuxi and this resolved the problem immediately.
Do a search on this forum - I wrote a really long detailed post about it.
Edit - here is one post about it
http://luminous-landscape.com/forum/index....raview+firmware
Edit - and here was the conclusion which all works now
http://luminous-landscape.com/forum/index....showtopic=34515
Edit - First thing you need to do is to check what version Firmware your monitor is running.
Thanks, Josh. I just checked on the firmware version using the Naviset software and it is 1.0.20. I have a call into NEC tech support. I am waiting to hear back from a technician but the contact person said I may have to send the monitor in for service. Sure!
Update: NEC Tech Support agrees that the issue is the firmware with the early 2690WUXi monitors from 2007, but they will not send a technician out to update it. They will send me a "refurbished" 2690WUXi with the updated firmware , and I then have to repack my monitor and ship it to them. I pay the shipping back to NEC. Bottom line is that NEC renders my monitor useless and then refuses to send a tech out to fix the issue in the field. NEC would not even agree to let me take the monitor to a local service facility for a firmware update. They said that is only for 32" inch and up LCDs. This is my reward for being an early adopter of the 2690WUXi and paying way more for it than anyone else has: over $2,000. My next monitor will be an EIZO!
I want to thank you again for providing such helpful information. You are in Australia and identified the crux of the problem for me in the US very quickly. The internet is an amazing thing. I really sympathize with what you went through before the issue was identified and resolved.