Programs disappear from the menu on Ubuntu after I install new software?
 

Hello! Sorry if these seems like a silly question,But im very new to Linux, (Ubuntu 10.04.3 LTS)literally installed it day before yesterday,and Im having trouble with my Menu.
It seems that everytime I install something new,an old program will disappear from the menu. I
Like for instance I installed a program for education. Half of the programs in the sound and video catergory are now gone!
But when I go to the software center to reinstall it,It informs me its still on my computer,and only gives me the option for uninstall. But its not in edit menu,or any of the programs lists,so Im very confused. has anyone else encountered this? and could someone please tell me,where these programs are going,and how i can get them back?

Do you happen to mean the Ubuntu Software Center? If not, do you know which distribution of Linux you have? There are several "flavors" of Linux, so to speak, such as Ubuntu, Debian, Red Hat, Fedora, SuSE, etc. So we would need to know which distribution you have.

It also would help if you could tell us what program you installed, and then which programs disappeared from your menu.

Its random which programs disapear,so far things like dragon player,VLC and Abiword are gone. Along with a lot of others (Cant remember them all right now.)
Yes the software center,I said the version in the beginning of the post,Ubuntu 10.04.3 LTS

What happens if you run sudo dpkg-reconfigure from a terminal on one of the applications that disappeared from the menu? i.e. sudo dpkg-reconfigure abiword