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Firefox won't open its own XUL file or XPS files on Vista OS

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I have been using Mozilla Firefox as my browser but when I try to open a downloaded file from Firefox labelled as a .XUL extension the file will not open. I am using a HP Probook laptop (HP 6450b) with a Vista business OS. I also cannot open XPS files. I hope you can help.

I have been using Mozilla Firefox as my browser but when I try to open a downloaded file from Firefox labelled as a .XUL extension the file will not open. I am using a HP Probook laptop (HP 6450b) with a Vista business OS. I also cannot open XPS files. I hope you can help.

Chosen solution

Firefox uses the .xul file extension for some internal files. To open such a file in Firefox for display you would have to use the view-source: prefix (view-source:file:///).

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Chosen Solution

Firefox uses the .xul file extension for some internal files. To open such a file in Firefox for display you would have to use the view-source: prefix (view-source:file:///).

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Thank you for your help.

                                        KeithatHowrah