Solution:
Delete completely the LimeWire installation directory.
Then open regedit and locate this key:

HKEY_LOCAL_MACHINE
SOFTWARE
Microsoft
Windows
CurrentVersion
Uninstall

Look at the list of keys (folders) and delete all entries named "LimeWire" (possibly with a version number)

In the same key as above, locate the subkey named "InstallShield Uninstall Information"
Search for those keys (folders in the tree) like "{0D9AB36C-333D-4188-8BBD-CF8BF996512C}" whose content on the right pane indicate a "StatusText" string set to "LimeWire Setup is preparing..."
Note the value of this numeric key!
Delete this numeric key (select that folder and press Delete).

Then return to the top of the list of keys in the Uninstall key (folder), and search the numeric key.
Its content on the right pane should indicate a "DisplayName" string set to "LimeWire" (or "LimeWire Pro").
Delete that numeric key.

Close RegEdit.

Reinstall LimeWire: InstallShield should not give you the option to uninstall or repair the installation.

Please reinstall LimeWire in the exact same directory name as before you deleted it. This will avoid letting extra garbage in the Windows registry...