The adaptor only displays the naive resolution sometimes

[lazaf]

Hello
I am using the adaptor output to a 22" Dell monitor.
The naive resolution of this monitor is 1680X1050.
There is a 1680X1050 option in my Display panel.
Unfortunately, the monitor goes to Energy Saving mode(blank) most of time of the time when I chose 1680X1050 (or anything higher than 1440X900).
However, when I was using it yesterday, it shows the naive resolution(1680X1050) without any problem.
So, I am wondering if it is a driver problem or the adaptor problem?
And I have attached my debug info.
Thank you very much.