Treeviewer doesn't load in Firefox

Dear TLA team,

I’m using the latest version of Mozilla Firefox under Windows 7. When trying to load the treeviewer, I get the following error message:

"Incompatible magic value 1008813135 in class file lams/applets/treeviewer/IngestNodeSelectionTreeviewer

Is there any help or bug fix available for this? If not, what else can I do to access the DoBeS corpus?

Thanks in advance,

Friederike