Random Standby With VGA Input?

I've recently bought a cable that can convert the video signals from my Nintendo Wii games console to VGA for my pc monitor. The monitor i'm using is an AOC 22". It has a DVI-D input, which I use for my pc, and a VGA input, which I have plugged the cable into. The monitor supports Digital and Analog. However, when using the analog input from the games console, the screen will randomly go blank for a few seconds, about every 5 or 10 minutes. I have kept open the monitor's menu settings, and found that it also disappears when the screen goes black, as if the monitor was on standby.
Does anyone know why this is happening? It's quite frustrating as it seems to happen more frequently the longer the console is turned on.
If anyone could help it would be greatly appreciated.