I’m afraid you have to reinstall LotusNotes.
Do not install both Lotus Notes 7 and Lotus Notes 6.x on the same machine. Instead, upgrade Lotus Notes 6.x to Lotus Notes 7. If you need to install both Lotus Notes 7 and 6.x on the same machine, be aware that this installation could have adverse effects on the operation of the 6.x Client that was previously installed, for example, OLE/COM settings will point to the Notes 7 directory, default email client settings, etc. With that understanding, follow the steps below to install Notes 7 on a machine that also has 6.x installed NSF Open File Tool http
You must have local administrator privileges to complete this procedure. These instructions apply to single user installs only: they do not apply to multi-user clientinstalls.
1. Shut down the Notes client and all Notes-related tools, utilities and add-ins running on your computer.
2. Rename the Notes 6.x directory. Notes 6.x is typically installed to \Program Files\Lotus\Notes on Windows. For example, you could rename the directory "Notes6."
3. Rename the entire Notes registry key HKEY_LOCAL_MACHINE\Software\Lotus\Notes. For example, you can rename it HKEY_LOCAL_MACHINE\Software\Lotus\Notes6
4. Rename the entire Installer registry key HKEY_CURRENT_USER\Software\Lotus\Notes\Installer. For example, you can rename it HKEY_CURRENT_USER\Software\Lotus\Notes\Installer6
5. Run the Notes 7 install program (SETUP.EXE). Select new locations for the program and data directories. For example, you can select \Program Files\Lotus\Notes7 and \Program Files\Lotus\Notes7\Data
6. During the install you may see an error message ""Error 1905.Module c:\program files\lotus\notes\nlsxbe.dll failed to unregister. HRESULT". Click OK andinstallation will proceeed.
7. When the install program has finished, rename the 6.x directory back to the original directory name, for example, \Program Files\Lotus\Notes)