Problem connecting Laptop to Samsung HDTV

HI,

I have a Samsung LE40R88BD HDTV & a Advent ERT2250 Laptop running Windows Vista.I am trying to connect bthe 2 together using a 5mtr VGA lead.

The problem im having is when i change the TV source to PC it dispalys no signal and then goes into standby,just briefly before this happens i sometimes can see the windows page displayed.i have tried everything i can think of to resolve the issue but have drawn a blank.We have another laptop in the home it is a Fujitsu Siemens Amilo Pro running windows XP,it has no problems connecting to the same tv using the same VGA lead.

Any Assistance will be greatly appreciated.

Regards Paul.