PC hesitates responding to mouse request

What can I do with an IBM Thinkpad that does the following: When you click on an Icon, even a submenu in the start window, it hesitates in accepting the mouse click and position. IBM has changed the board twice, the harddrive and the keyboard. The system has been restored from the original cd. Therefore, any thoughts as to what is causing this because it is quite upseting to, in powerpoint, click on insertion, and the machine hesitates 5 seconds before opening the window ?