hello i recently built a new pc and used a Connect3d Radeon X600 PRO as the graphics card.
i have installed the latest drivers for this graphic cards but still have problems.
these problems are that the graphics card will sometime switch the screen on and then of, the system will hand justa after booting up but will be fine after a couple of mins.
when using say google news and i scroll down the page it takes ages to scroll down and does it like in 'slow motion'
what could be the problem, i am running windows xp professional

Verify that your motherboard's BIOS is up to date.
Verify that your Windows Updates are all up to date.
Verify that you have the latest version of your Chipset drivers installed.
Verify that you have .NET installed (required by the ATI control panel).
Verify that you have the latest version of the ATI drivers installed.

1) that system 'hang' may not be a hang at all. it may be the screen being displayed on a different moniter port, a problem i've had before.

2) if it just randomly refreshes your screen, like off and back on in a matter of seconds, thats because the refresh rate of the moniter that you set in windows is too high, and the moniter can't keep up, it happens with CRTs more than LCDs.

3) if its doing the slow motion thing, thats probably windows, not the card.

i had this same exact problem on 2 of my comps when my video driver wasnt installed... maybe try using an older vid driver? and whose driver are you using?

I go with the others, driver problem.
De-install the driver and install it again without ATI control panel.
I also would check the voltage on the PCI-E/AGP port.

I should reiterate that not only the video drivers need to be properly installed, so do the chipset drivers. If the AGP drivers or PCI-E drivers are not properly installed, this can have an effect on the video drivers.

Yes, I'd say it's 99.9% an improperly installed or corrupted driver. Deinstall it, and use DriverHeaven's DriverCleaner (freeware) to cleanup any remaining files and registry entries. Reboot, cancel out of Windows' automatic launching of the New Hardware Wizard and then proceed to Device Manager and manually update the drivers with the latest versions.