I have a flat-panel Dell monitor (model E198WFpv) with a native resolution of 1440 x 900. I have it connected to a Dell Optiplex 210L desktop computer with Windows XP Pro SP3. There is no additional video card -- I'm just using the stock hardware that came with the computer. The adapter shows up as Intel(R) 82915G/GV/910GL Express Chipset Family.
Everything worked fine until I temporarily swapped out the flat-panel for an old CRT monitor. I adjusted-down the resolution when I used the old monitor. Now that I've re-connected the flat-panel to the PC, I can't set the display settings to the monitor's native resolution -- 1440 x 900 doesn't appear as one of the choices. I've tried re-booting. I've tried scanning my hardware for plug-and-play devices. I also downloaded and installed Dell's driver, which seemed to have no effect whatsoever.
I've also tried Display -> Settings -> Advanced -> Monitor -> List all modes. It's not in the list.
What am I doing wrong, here? And how do I fix it?