Problem with external monitor on Macbook Pro

Hello,

I am trying to connect my Macbook Pro (bought Fall 2009) to a external monitor - an Asus VW222.

I use a VGA converter which I bought together with the mac, I plug a VGA cable in the converter and then I plug it into the display port of the mac.

I do get an image on the Asus monitor, but it is not very useful. It is flickering between a yellowish color everywhere and normal colors. Moreover I cannot change the resolution. If I set the resolution to 1680*1050 (the Asus' native res) then the image still looks scaled/grainy and it doesn't fit on the monitor. The top menu for example is outside of the screen and the whole image is slightly moved to the right so I have a black bar to the left.
If I set the resolution to the mac screens native res, 1440*900, the image fits on the Asus but is of course scaled.

I tried go to system preferences and calibrate, but it did not help.

Can someone help me identify the cause of this?

 

Thanks for your replies

I had it at mirror display mode. I tried two different VGA cables - both kinda old but nothing seems to be wrong with any of them when looking at the pins or anything.

I know the Asus monitor is working since I have been using it until yesterday with no problems, but my graphics card in my stationary PC died yesterday. I've been using the Asus with a DVI cable since I got it, and have never used anything else. Could the problem be that the Mac for some reason doesn't work when being connected through VGA with the Asus?

I also tried an old monitor which I know works - this one only got VGA connection. On this monitor the colors seem to be okay, but I can't get the resolution right. It should be running 1280*1024, but when I do that I get black bars on top and below the screen. It's not a widescreen monitor.

Also the trick about closing the lid of the Macbook pro and then pressing a key on an external keyboard to wake it up doesn't really work with this monitor. I can only have both screens (the macbook and external) show something at the same time.

 

Isn't it odd that both monitors work fine with other computers? Also when using the VGA port.

To me that looks like its one of two options.

1) The VGA adapter is faulty
2) The displayport is faulty

I really do hope it's option 1) though

On the old monitor I tried, besides the Asus, its only the resolution that gives me trouble. The colors on this is fine. I can only achieve a correct, but scaled, picture when using 1024*768. When i go to 1280*1024 which is the monitors native res, I get two black bars in the top and bottom - but the picture doesn't seem to be distorted though. Else than that it looks okay on the old monitor. The asus is another story though as I mentioned earlier...