The Microsoft Java Virtual Machine, or MS Java VM, is used to run Java applets that can be found on web sites. When you visit a web site that has a Java applet, the MS JVM will compile and execute that applet on your machine. Microsoft no longer supports the MS JVM and it has become obsolete. There have also been known security issues with un patched version of the MS JVM we advise that you remove it and install the safer SUN JVM as an alternative. If you have Windows XP SP1a installed on your computer, then you do not have the MS JVM installed on your machine.