GMod won't start

[Orthone]

Specs-
Proccessor: AMD Athlon(tm) 1.60 GHz
Ram: 1535 MB
Operating System: 32-bit Windows Vista
Graphics Card: Radeon X1650

I have reinstalled steam and GMod, nothing seems to work.

What happens is when I start GMod from steam, it says "Preparing to launch Garrys Mod..." for about 20 seconds. It doesn't pop up with any message and it is deleted from the Proccesses in task manager.

Any help?

Edit:
Fixed thanks to yuyuimg, the fix is the below post.

[yuyuimg]

I have the Same problem D:

Edit:

Found a fix, in steam right click on the garrysmod icon and select properties,
click on "Set launch options" and write in the box "-fullscreen" with out the quotes ("")

[Orthone]

[QUOTE=yuyuimg;19375544]I have the Same problem D:

Edit:

Found a fix, in steam right click on the garrysmod icon and select properties,
click on "Set launch options" and write in the box "-fullscreen" with out the quotes ("")[/QUOTE]

Thanks, that fixed it right up.