Thank you. Unfortunately it didn't fix my issue, but I did discover that it is only a problem on some Android 4 versions, no issues on newer versions. The error only happens on a Droid Ultra Android version 4.4.4. I'm OK with just saying it needs to be newer, but if anyone is interested here is the dump from the error:
java.lang.IllegalArgumentException: Cannot have both DTEND and DURATION in an event
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:167)
at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:137)
at android.content.ContentProviderProxy.update(ContentProviderNative.java:560)
at android.content.ContentResolver.update(ContentResolver.java:1364)
at edsmith.calendar.Calendar.UpdateEvent(Calendar.java:3121)
at org.techteam.mst.calendar._modifycalendarevent(calendar.java:285)
at org.techteam.mst.mstcalls._editcommhistory(mstcalls.java:4861)
at org.techteam.mst.categoryview._btnconfirmedit_click(categoryview.java:2737)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:710)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:342)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:249)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:139)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:170)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:166)
at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
at android.view.View.performClick(View.java:4466)
at android.view.View$PerformClick.run(View.java:18542)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5097)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)