When closing Lotus Notes (or if notes has crashed) and re-opening the software, you may receive the following message 'An error was encountered while opening a window' preventing you from using the Software.
There is a quick fix for this however:
1. Close Lotus Notes
2. Open Task Manager by right clicking the task bar and clicking Task Manager
3. Choose Processes
4. Find and select ntaskldr.exe
5. End the process
6. Close Task Manager
You should now be able to open Lotus Notes as normal.