Hi, a disk check takes approx 25 seconds on my EZ 320.
During the check the activity LED flashes orange and green. When complete I get a popup saying "Disk check completed".
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As far a changing the Workgroup name, I have no idea if that's possible, but it hasn't caused me any apparent difficulties, even though my PC's have a different Workgroup name.
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Also I've never seen the status change to disconnected on mine.
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Sorry I can't help you more, good luck.