The Microsoft VM supports only applets under version 1.1

If you allow the Microsoft VM browser to open the applet that you compiled in the high version, you will see class <XXX> not found in the status bar and the Java console (if you are enabled) or Java.lang.NoClassDefFoundError errors and Java.lang.ClassNotFoundException exceptions.

You can use the Javac <XXX.java>-source 1.3-target 1.1 to build Java classes that the Microsoft VM can load, but that's far from enough: there are a lot of features that are not available in the lower version of Java. It is often the case that you will see some strange problems with the applets that you have written in the IE kernel browser. At this point, if you open the Java console, you will often see a similar error without the class, and so on, because you are using classes that are not supported by the Microsoft VM.

Another important thing: third-party browsers with IE as the kernel (such as surfing, Greenbrowser, windows of the world, etc.) do not use it because you are set to use the sun's JVM in IE, and I use the JVM on my computer anyway. The JVM icon appears in the tray when browsing the applet with IE. When roaming, there is no JVM icon, and the applet cannot be displayed, consistent with the use of the Microsoft VM. So I'm sure the Third-party browsers are using a Microsoft VM. I believe that these excellent third-party browsers will be improved in the future.

In addition: I am using XP SP2, is not a high version of Windows or Vista will not have this situation. I don't know.

But at least for now, I'm afraid it's not easy to make a very compatible applet ...