Well, it could be anything really. I'm not saying I could give you a defintive answer even if you supplied all the information but it is likely a 'feature' of the particular combination of souce types, plugins and source count you are using.

For example. If I try to render more than 3 or 4 animated stills within some of my HDV footage, using a certain plugin I get 'unknonw errors' out of Premier Pro 2. My workaround is to render the timeline piece by piece. once rendered ok I can export fine.

This is not the same as your issue but I mention it as an example that it could be a combination ofmedai types, how many there are and the plugins used.

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