This happens when while un-installing the CodeWarrior tool, the installer crashes in between. The files are removed from the hard drive and the icons are removed from the Start menu. Also, the CodeWarrior tool does not appear in the Add/Remove Programs panel. But, your system will not let you install another version of the CodeWarrior tool, as there are still some files remaining.
To remove the remaining CodeWarrior files:
msiexec /i[ProductCode]
The CodeWarrior setup dialog box appears.
You can now successfully install another version of the CodeWarrior tool.