OK - so I got it fixed.
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Ran a full ccleaner registry sweep AFTER uninstalling all versions of Sketchup from the machine
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Reinstalled the FREE version
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Tried to start the free version, Got the same old "sketchup pro trial expired screen"
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Went into regedit
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Searched for sketchup 8 entries
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At the bottom of those entries appeared this item: Welcome Dialogue
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Within Welcome Dialogue there are two entries - the bottom one is AllowRevertToFree
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Go to edit command, then to edit
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Change the value from "0" to "1"
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Close regedit
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Reboot machine (I just did this to be certain the change "took"
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Start machine, click on Sketchup 8, and HOORAY! The option of "revert to free" now appears on the pro trial expired startup screen.
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Back to sketchup!
Hope this helps someone with a similar problem. Thanks for all your help!
John and Mike, Indiana, USA