Use the keyboard and mouse to reset the controls to defaults and try it again. Or, maybe fix it in controller options. All else fails, delete the ini and prefs files in My Games/Skyrim, backing up any changes you may have made to add back later before deleting. Let the game make some new files and then try it again. Some ini changes to change mouse behavior mess with the controller.
Also, make sure you have the Microsoft drivers for your controller. W7 should have them already, but XP may not.