The splash screen is not shown in 64-bit Linux (do not know about solaris) using 16-bit color depth scheme. Only explicit invocation of update() makes the splash screen appear. It does not matter how much time passes before the update method is invoked.

The following code helps to observe the splash screen start failure:

        System.out.println("Sleeping for " + sleepms + "ms...");
        sleep(sleepms);
        SplashScreen ss = SplashScreen.getSplashScreen();
        System.out.println("createGraphics()");
        ss.createGraphics();
        sleep(1000);
        System.out.println("update()");
        ss.update(); // Splash screen appears at this point
        sleep(2000);
        System.out.println("ending in 1sec");
        sleep(1000);

The sample code is attached.
For your convenience I also attach the bundled jar containing the image and the code (test-89x89.jar)


 The failure is observed at least for JDK6u25 and JDK6u23.
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java version "1.6.0_25"
Java(TM) SE Runtime Environment (build 1.6.0_25-b04)
Java HotSpot(TM) 64-Bit Server VM (build 20.0-b11, mixed mode)
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 Not observed for JDK6.0 b105
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java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) 64-Bit Server VM (build 1.6.0-b105, mixed mode)
========================================================

More info:
- observed in KDE 4.3.5 and GNOME 2.3
- not observed in 24-bit color mode
- uname -a:
========================================================
Linux green 2.6.31.14-0.6-desktop #1 SMP PREEMPT 2010-12-10 11:18:32 +0100 x86_64 x86_64 x86_64 GNU/Linux
========================================================
- xwininfo:
========================================================
  Absolute upper-left X: 0
  Absolute upper-left Y: 0
  Relative upper-left X: 0
  Relative upper-left Y: 0
  Width: 1280
  Height: 1024
  Depth: 16
  Visual Class: TrueColor
  Border width: 0
  Class: InputOutput
  Colormap: 0x20 (installed)
  Bit Gravity State: NorthWestGravity
  Window Gravity State: NorthWestGravity
  Backing Store State: NotUseful
  Save Under State: no
  Map State: IsViewable
  Override Redirect State: no
  Corners: +0+0 -0+0 -0-0 +0-0
  -geometry 1280x1024+0+0
========================================================