Diamond Radeon card problems

Hello,

First post to this group. I installed vista last week and upgraded my
ancient video card to the Diamond Radeon HD2400Pro AGP version. my
motherboard is about 6 years old so i had to have an agp card.....

occasionally, when i boot up the computer, i get no video at all.
computer is running, but there is no video input. the only way i have
found to reset it is to take the video card out of it's slot and
reseat it. then the video comes up when i reboot.

the monitor is a viewsonic VP201 with both vga and dvi inputs.
i had used the vga because my old video card only had vga inputs, but
the Diamond has only DVI inputs. it came with an adaptor so i used
that to attach the setup.

I'm wondering if that may be the problem.... maybe the video card
doesn't like the adaptor
the monitor came with a DVI cable, but my desk is set up to need
longer than a 6' cord.. i could go buy a 10' cable for about 50 bucks,
but i thought i would start asking questions about this before i spent
money needlessly.

though as i understand it, the DVI cable should be better for the
monitor anyway as long as the video card has a DVI input.

any other issues that might be the cause here?

thanks,

dave