I first saw this issue on my first Vostro 1400. While I awaited the replacement, I messed around with it quite a bit. This screen resolution reverting to 1024x768 appears to be caused by a certain OS update from Microsoft. I couldn't duplicate this issue with a fresh OS install, until after I let it grab the updates from Microsoft. I tried all different drivers combinations (original
Dell drivers, drivers direct from Intel chipset and such), all eventually leads to this problem.
Also, sometimes, I'd say around 1 out of 10 times, after resuming from sleep, I could no longer adjust the screen brightness using fn+up/down. This is related to the screen reverting to 1024x768 issue.
The fix? Close the screen and reopen it! Note that I have my screen close action set to "do nothing". The default is when you close the screen, your laptop goes to sleep. Must make it do nothing, otherwise it'll go to sleep obviously
By closing the screen it somehow refreshes the video card and/or the screen.
This is not just on my Vostro 1400. I have this same problem on my XPS M1330. The same 1 out of like 10 times the screen resolution goes to 1024x768 and sometimes also lose brightness control. Close the screen and back to its native resolution and re-enables the screen brightness adjustment.
I know it's not a "fix", but MUCH easier than to navigate to your screen properties and manually change the resolution back. This seems to me is a bug from Microsoft and one of its OS updates.
Another note, Vista has this TMM task scheduled to run on every startup. With it running, upon resuming from sleep, there's a 3-5 seconds delay from the screen flickering. To get rid of this annoyance, disable the task "TMM" in your Task Scheduler. After you disable the TMM, your screen will come back on instantly. Thank flamenko for this one.
Screen resolution resets to 1024x768 on resume? Quick fix!
