The brightness adjustment function on the E151FPb monitor that I got with my new 4600 (w / 64MB NVIDIA GeForce MX 440 AGP 8X video card) simply does not work.  It seems to be "stuck" at a preset level that will not change; much too  bright for me.  Thanks to Dell, have been through two replacement E151FPb's, one video card replacement, and two updated video card driver downloads.  Have repeatedly tried all  the monitor adjustments (e.g., autoadjust, factory reset, lock function unlocked, etc.) without result.  The brightness level remains "stuck" and will not change.  Otherwise, the monitor works just fine (as does the computer).  What else could be causing the problem?  Are we missing some simple (but elusive) "fix" in all of this?  Is the onboard video overriding the video card (which could portend a motherboard defect)?  Interestingly, I do get a pretty good picture for a fleeting moment when I push the autoadjust button, but  that pretty good picture "washes out" due to  brightness in a couple of seconds.  Dell customer support seems to be a loss as to what to do next.  Any thoughts / ideas?