I tried to install mplayer under Mandrake 9.0. However, after I clicked install, rpmdrake says "Everything is already installed(Is it supposed to happen)" etc. I tried to run mplayer, nothing happened! I've gone thru the errata and found one entry for this error. But everything seems to be ok in my machine as I have installed VariCAD etc nearly without any difficulty. So I tried to remove the software from my machine, and bingo, mplayer was not there in the installed list of packages to remove! Anyone have any idea? Any help would be greatly appreciated.

As an aside, I've noted a strange behaviour of Mandy 9! What happened is after an expert install, I've installed VariCAD, and menudrake automatically added it under Applications menu. Ok great I thought. Then I've updated urpmi and gurpmi from the updates, and that entry of VariCAD from the menu is gone!!! I've to add it manually again. Is this a bug, or my stupidity? I fear the latter one!

Go to a console and do the following:
rpm -qa | grep mplayer
If any mplayer packages don't show up, it's not installed. If they do, do the following:...
gmplayer
...and if nothing shows up, rpmdrake is lying to you, mplayer is not installed. Install your package(s) this way:
rpm -ivh followed by the complete path and file name. If any dependencies, it will tell you.
As far as your menu problems go, I think the best remedy is to manually edit your menu, if you can find it. It might be in a hidden folder in your root directory.

maybe it's installed but the symlink is messed up?(shoudn't be with the rpm, but you never know) Also which rpm version did you install? was it mandrake specific, or a redhat rpm?