for some reason some pupils at my school can not open their saved worlds, it says

Unable to load world: \\***-**-***\StudentWork\Intake 2008\08JBloggs\Year 8 Folder\ICT\alice\Ollies World Of Vertu And Camel Eggs.a2w
Alice version: 2.2 9/1/2008
Throwable that caused the error:
java.util.zip.ZipException: error in opening zip file
at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.<init>(Unknown Source)
at java.util.zip.ZipFile.<init>(Unknown Source)
at edu.cmu.cs.stage3.io.ZipFileTreeLoader.open(ZipFil eTreeLoader.java:66)
at edu.cmu.cs.stage3.alice.authoringtool.AuthoringToo l.loadWorld(AuthoringTool.java:1905)
at edu.cmu.cs.stage3.alice.authoringtool.AuthoringToo l.loadWorld(AuthoringTool.java:1872)
at edu.cmu.cs.stage3.alice.authoringtool.AuthoringToo l.showStartUpDialog(AuthoringTool.java:1340)
at edu.cmu.cs.stage3.alice.authoringtool.AuthoringToo l.openWorld(AuthoringTool.java:1354)
at edu.cmu.cs.stage3.alice.authoringtool.Actions$2.ac tionPerformed(Actions.java:90)
at javax.swing.AbstractButton.fireActionPerformed(Unk nown Source)
at javax.swing.AbstractButton$Handler.actionPerformed (Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed (Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unk nown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mou seReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent( Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(U nknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unkno wn Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierar chy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Can anyone help?