I'm having the same problem as this guy, except that I wasn't able to fix the problem the same way he did. I have a Toshiba 5105-S501. Has anybody with this laptop been able to get X working correctly in 1400x1050? I've tried using the HorizSync 30-100 and VertRefresh 60 setting, but it won't work with this laptop apparently. Other than that, I have the same XF86Config-4 as lionelb.
If anybody has some ideas, please let me know. Thanks!