Many times when Lotus NOTES terminates abnormally, I am unable to restart it and try to use the task manager and guess which are the processes to kill. This sometimes works but most of the time I end up having to reboot my windows.
A more efficient way is to just use the NSD (Notes System Diagnostic) utility. NSD.exe can be located in the lotus notes program folder. To ensure all the just type nsd -kill. This will kill all the processes related to Lotus NOTES and you should be able to restart Lotus NOTES without rebooting your PC.