• OS PATH environment variable is incorrect
• Check if the System Environmental variables IBM_JAVA_OPTIONS and _JAVA_OPTIONS exist (My Computer Properties -> Advanced -> Environment variables).
• Review notes.ini and check for any hooks/addins, if found, comment them out by adding a semicolon in front of each line, and test launching Notes:
  • EXTMGR_ADDINS=
  • AddinMenus
• Check the XML trace logs under data/workspace/logs for any errors
• Launch Lotus Notes using the following parameter:
  • Using command prompt window
  • Navigate to the Notes program directory
  • Run "notes -RPARAMS -clean," does Notes launches?
• Test launching in Basic Mode (nlnotes.exe from program directory)
• Reboot the machine in Safe Mode and test if Lotus Notes standard launches.
• If this is only affecting one user, rename the workspace directory under Notes/data and test if Notes Standard launches
• If none of the above help, collect the following and open a PMR to further troubleshoot this launch issue:
  • Notes.ini
  • Log.nsf
  • Data\workspace\logs (All its contents)
  • Data\IBM_TECHNICAL_SUPPORT\ directory (with all its contents)

Use Killnotes.exe or Zapnotes to kill any hung process. If you don't have any of those, you can open the Windows Task Manager and end any process related with Notes (notes.exe, notes2.exe, ntaskldr.exe, etc)

After killing every Notes process, try to open Notes again.