Any card will do this. Not just ATI or NVidia. It is related to the drivers and the state of the Windows registry. It also varies based on what is running in the background of the system.
I have an ATI card in my work and home systems and can ALT-TAB all day long without any issues.
As to solving the issue, it is difficult. Typically it is related to upgrading video drivers without taking care to remove previous drivers before upgrading.