i think yahoo messenger has issues with ubuntu. try gaim or pidgin whatever the name
all the debs i used never work so i downloaded an rpm and used
alien to convert it, it work but it didn't make an entry in the menu, i had to look for it in the system
what does that say about ubuntu's package manager? If you can't install the debian package, .DEB, but you can install a redhat package using alien .rpm, what does that say about the package manager?