Firstly we need to see if this is software or hardware related. The only problem with this is, that you will need to go through some extensive installations.
1. First try uninstalling your drivers completely and reinstalling them. Before you do this, go to AMD's website and find the most recent drivers for your card. Once you have the drivers downloaded proceed to uninstall your drivers. To do this go into your device manager. To bring up your device manager click your Start Button > Right Click My Computer > Click Properties > Hardware > Device Manager. Once there you will need to find Display Adapters. Click the Plus Arrow to expand the list and find the name of your Video Card. Right click the Name > Properties > Click Driver Tab > Uninstall. After you have uninstalled, restart your computer. Once you have restarted you will log on with a horrendously large resolution. Do not freak out about this resolution just deal with it. After restarted proceed to reinstall your drivers. Once reinstalled you will need to restart your computer once more.
2. If you have reinstalled all drivers related to your graphics card and the problem still exists, you could be faced with hardware problems. Depending on how old your graphics card is you might need a new one. Try reinstalling your drivers from scratch like I have posted above and see what happens. Please reply after you have done that letting me know if it has worked.
Hope this helps for now,
-Agent2106