DELL D610 dual monitor problems

hi,

I have a dell D610 latitude laptop with a MOBILE INTEL 915GM/GMS, 910 GML Express chipset family graphical adapter. i have two problems:

the first problem is that: (monitor displaying no thing)

when connecting a new monitor (DELL 17 LCD) to the laptop, the computer shows that the desktop is extended but i can' t see anything on the screen.

however if i use the zoom tool found in the control panel ->INTEL GMA Driver for mobile i can see the content of the monitor on the laptop screen.

the second problem is that i can't set the resolution higher then 800x600

Sometimes (without knowing the reason) when setting the monitor resolution to 800x600 i begin to have an extended desktop on the monitor, however if i try to higher the resolution above 800X600 the monitor goes black and stop displaying any things

thanks for any help