Dual monitor problem?

I installed a new graphics card (Nvidia GeForce 7300 LE), which has a DVI port. I got a 2-way DVI to VGA splitter and plugged in my two monitors for dual desktop. At startup, the dual monitor setup always works, but after a certain amount of time, one of the monitors stops being recognized and the display reverts back to a single monitor (the screen that is no longer recognized is not the same one everytime). The only way for me to get my two displays to show again is for me to restart my computer. Is there a way to make it so that both displays are always recognized and functioning properly? Oh yeah... and I have Windows 7 Professional 64-bit. I also tried the same setup with an ATI FirePro graphics card (this card had 2 DVI ports with VGA converters, so I used those), and I was experiencing the same problem. I even went into the BIOS and made sure my active video defaulted to PEG instead of Auto, and still no luck. Does anyone know what could be causing this strange problem? Any help is much appreciated. Oh... and my monitors are both LG Flatron L1943PE.