Second monitor not displaying anything

Today I turn on my computer and my second monitor doesn't display any image anymore. I can set it and all in the resolution settings. In fact, everything looks normal except the fact that it doesn't display anything. I can move windows to the other screen and when I do a printscreen and paste it in Photoshop everything looks normal.

GPU: Radeon HD 5750
I have two Samsung SA 350 monitors.
One is plugged in HDMI to HDMI, the other is normally plugged in VGA to VGA (the one not working).
I have tried everything I can think of to make the second monitor display an image. Update the drivers, change many settings in Catalyst Control Center such as the refresh rate.

On the back of my case, I have one HDMI, one VGA and one DVI port (Antec 900 case). If I unplug the VGA to VGA cable normally used for the second monitor and put a DVI to HDMI cable instead, everything works fine. The thing is, I sometimes want to display my desktop on my TV using the DVI to HDMI cable, which is now used for the display of the second monitor.

In short:
Setup normally used (second monitor doesn't display anymore):
First monitor: HDMI to HDMI cable
Second monitor: VGA to VGA
TV: DVI to HDMI

Setup that works now:
First monitor: HDMI to HDMI
Second monitor: DVI to HDMI
TV: unplug HDMI from second monitor and plug it in TV

So the second monitor displays an image when it is plugged with a DVI to HDMI cable but does not display anything when its plugged with a VGA to VGA cable. I would like to get back to the first setup.

If nothing really works, is there any kind of way to get a VGA to HDMI converter working with this? I would plug the HDMI output in my monitor and the VGA output in the back of my computer. I know it is usually used in the opposite way (HDMI in the back of the case and VGA in the monitor) so I was wondering if it would work.

Thanks.