Windows 7 - 1440x900 resolution issue

I've had Windows 7 Ultimate 64-bit running for almost a year now with no issues at 1440x900 on my junky 19" monitor. That's hooked up from the VGA port on my monitor (the only input) to a VGA-DVI adapter that came with my video card--an NVidia GeForce 8800GT. Yesterday, I decided to make use of the card's 2nd DVI and, using a DVI to HDMI adapter, ran the 2nd port in to my 32" Sony TV (via HDMI, of course). Everything seemed fine and dandy at first--the monitor ran fine, and I was able to extend my desktop on to the TV.

When I was done with that, I shut off the TV & my computer, but left the HDMI cable plugged in. The next time I started my computer--19" monitor only--the resolution defaulted to 1280x1024 or something like that. I right-clicked on the desktop to change the resolution, and 1440x900 was no longer an option. Only an hour or two earlier, it had been available (obviously) when I was messing around with the configuration of the 2 displays. So I unplugged the HDMI/DVI cable from my computer altogether, restarted, and got the same problem. Updated the driver on my NVidia card, restarted, and got the same problem. After reading another thread, I found out how to create a custom resolution, and everything's hunky-dory now in that regard. No more resolution to which I'm not accustomed messing with my eyes. But how can I avoid having this problem in the future? Will it delete the 1440x900 option every time I use multiple displays? Because that would be a major bummer.

Thanks to anyone who can help!