The problem is manifested by the following exception in the log of the Java Proxy and/or the log of the Domino server:
java.lang.NullPointerException at com.ibm.icu.util.TimeZone.getDefault(TimeZone.java:700) at com.ibm.icu.util.Calendar.getInstance(Calendar.java:1613) at com.ibm.icu.text.DateFormat.get(DateFormat.java:942) at com.ibm.icu.text.DateFormat.getDateTimeInstance(DateFormat.java:736) at com.ibm.di.plugin.log.PWSyncLog.<init>(PWSyncLog.java:49)
To fix the problem open the lib/ext folder of the Domino server's JVM (for example, C:\Program Files\IBM\Lotus\Domino\jvm\lib\ext) and locate the ICU4J jars (there should be two of them - the original one of the Domino server and the one from the Domino Password Synchronizer). Remove the one named "icu4j.jar and restart the Domino server.
Some versions of the Domino server (8.0 and 8.5) ship with ICU4J version 3.4.5 (the "icu4j.jar" file in the "lib/ext" folder of the JVM). This version of ICU4J exibits problems on Windows when the "Automatically adjust clock for daylight saving changes" option is unchecked (Control Panel -> Date and Time -> Time Zone). More precisely, problems are observed when a non-zero DWORD value named "DisableAutoDaylightTimeSet" (before Windows Vista) or "DynamicDaylightTimeDisabled" (Windows Vista) exists under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation in the Windows registry. The Domino Password Synchronizer ships with a newer version of the ICU4J library that does not have the same problem. To fix the issue, remove the original Domino ICU4J library and use the one from the Domino Password Synchronizer.