It sounds like it might be your graphics card, check the driver maybe even reinstall the driver. I would first suggest looking for an update to the driver, windows update is suppose to let you know when new drivers are available, but sometimes you don't find out until months after it has been released and sometimes never also if you try to update the driver using device manager and allowing windows to search for it automatically chances are it won't find it even if there is an update available, so I would suggest checking the manufactures website yourself. Find out what version the driver is that you have installed, what the chipset is and search for a newer version, if you have an intel chipset then you could start here:
http://downloadcenter.intel.com/ they also have a handy little tool which will help determine the chipset type, located here:
http://downloadcenter.intel.com/Prod...D=861&lang=eng so that you can make sure you get the correct drivers. I only know about intel because that's what my graphics card is, but if you have a different manufacturer just go to their website and search support for downloads or drivers and you should find what you need. If there is a newer version available (and make sure it is for vista) then you should download and install the update. If no updates are available I would try to reinstall your current driver or if you have recently installed an update you may want to rollback the driver to the previous version.
