If you install Lotus Notes on a 64-bit OS (e.g. Windows 7) and wish to use the "IBM Lotus Notes Single Login" you noticed that you always will be prompted for an password, even though Notes Single Login is enabled in the Notes Client via File - Security - User Security.


This issue was reported via SPR# JZJZ7XA7FS (see technote Technote #1418129) and is solved in 8.5.2 FP2 like written here:


SPR# JZJZ7XA7FS (LO47208) - Notes Single Logon will not function on Windows 64 bit client OS due to an incomparability with the 32 bit Lotus Notes Client. With this fix, Notes Single Logon will function on 64 bit Windows client OS.