I have AdBlock Plus installed on my Nexus 7, using Chrome as the browser. With the proxy setting set to ABP, some websites return various http errors, even if ABP's filtering is turned off. I noticed this on several sites, including http://www.newegg.com/. After turning off the proxy settings for the wireless connection (ABP was still installed, just not used by Chrome), I was able to pull up Newegg without any issues.
Hardware: Asus Nexus 7 (that's the 2012 model, not the new 2013).
Android Version: 4.3.
ABP Version: 1.1.3.
Chrome Version: 29.0.1547.72
Chrome showing Http error 400:
My current ABP settings:
ABP for Android interferes with sites when filter disabled
Re: ABP for Android interferes with sites when filter disabled
I cannot reproduce this behaviour. If it still exists for you, please file a report at https://issues.adblockplus.org