Just a thought - if you use DHCP (or MAC allocation) then the LAN DNS server will be your router and the WAN DNS is your provider. This can cause issue so with devices like this I use a fixed IP and use Google's DNS (8.8.8.8 and 8.8.4.4).
If it keeps trying to scrape things that were already scraped, the nuclear solution may be to block internet access via your router for the Zidoo, and only allow access when you need to re-scan your library, lol. Although that's annoying af.
People experiencing the issue mentioned here should take a look to the thread below and share their own experience, that could help to solve it. http://forum.zidoo.tv/index.php?threads/ht4-slow-poster-refresh-issue.96356/