i have Vostro 1510 and until the begining of this week i could use dual monitor option. i don't know why, but now when i connect monitor to the vga out port, the computer recognize it, but i see no input on it. i tried switch resoulotion, but it's not working. i uninstalled the vga drivers (nvidia 8400m, latest), and i could use the external monitor or the laptop monitor, but not toghether. when i reinstalled the drivers, the problem returned. in ubuntu live cd, everything work perfectly, so it's not likely that it's an hardware problem. i don't remember installing anything that may cause this. i tried to use combofix just in case, but it didn't help, so i restored back. unfourunely have no system restore points from the period when it worked.
Lacking a disaster recovery plan leaves you few options. If all attempts to get back to dual monitors continues to fail and you're convinced your video card is functioning properly, what choice do you have but to wipe the drive and reinstall your system? If you take that route you need to strongly consider creating at least one system image once you get a stable, fully functioning, system. And always backup, backup, backup. Of course you could try a different video card and see what happens.
okay, an improvement now it flicker and not stable, and sometimes it disappear, but i can see output on some monitors. is there any thing i can try?
at first i also thought that this is hardware related problem, but then i found out that in other OS'es that i have (Ubuntu, and Mac OSX 10.7) dual monitor option worked flawlessly. so i think it might be something in my windows. i have the latest nvidia drivers installed, but still, not helping.
already tried that. reset all the nvidia setings, downgraded the resoulotions and the refresh rates when i see input in the 2nd screen, i see flickering and it lose the image after few seconds, then restore it, and again...
tried multiple monitors, same effect.can;t find any system restore before the problem occured. i have acronis image for my system before 4 months i think, but i want to try to find the problem before i do this.