the 1-2 inch area near the clock on taskbar is known as system tray as raven also said... the whole 1 cm wide bar is the taskbar where applications/programs minimize!!!
now let us know ur programs disappering from taskbar on minimizing them or they minimizing on the systray??
to this press clt alt del and bring up task manager and click on the program icon which is disappeared and click on "bring to front"
also check if you're using any application like minimizer-xp which minimizes all application to sys tray or hide their icons.... or anysuch "anti-boss" program!!