Null pointer exception when viewing previous version of page

Viewing an older version of a page in Page History causes null pointer exception:

2011-11-09 09:43:49,339 ERROR [http-8080-22] [renderer.v2.components.MacroRendererComponent] processMacro Unexpected err
or formatting macro: pagetree
– url: /pages/viewpage.action | page: 161288547 | userName: <me> | referer: http://<our_url>/pages/viewpr
eviousversions.action?pageId=61636717 | action: viewpage
java.lang.NullPointerException
at com.bnpparibas.confluence.extra.tree.PageTree.execute(PageTree.java:156)
at com.bnpparibas.confluence.extra.tree.PageTree.execute(PageTree.java:104)
at com.atlassian.renderer.v2.macro.ResourceAwareMacroDecorator.execute(ResourceAwareMacroDecorator.java:51)
at com.atlassian.renderer.v2.components.MacroRendererComponent.executeMacro(MacroRendererComponent.java:203)
at com.atlassian.renderer.v2.components.MacroRendererComponent.processMacro(MacroRendererComponent.java:169)
at com.atlassian.renderer.v2.components.MacroRendererComponent.makeMacro(MacroRendererComponent.java:67)
at com.atlassian.renderer.v2.components.WikiContentRendererHandler.handleMacro(WikiContentRendererHandler.java:1

The page in question was moved from another wiki space prior to the Confluence 4 upgrade.