Can't install trial versions - gives an error

[DullingWine]

Hi
I'm trying to install new versions of software from office enterprise or
expression web trial, and when i do, it says i have to remove any trial
versions of microsoft office software.
I do have trial versions of visio, and publisher but frustratingly, they
won't uninstall. When i try to remove them from add/remove programs I get:
"Setup could not finy any available products to install. Please contact your
system administrator"!

Does anyone know how to get round this?

Thanks

DullingWine