Foreign output when Login snippets redirects occurs

Hello everybody!
I have strange foreign output like "88ba" before the HTML document starts and "0" after HTML document ends when snippets of Login package send redirect if error.
Digits always unique, e.g. "8911" "0"; "890f" "0"; "8910" "0" ...
Also, there is something strange with URL-string.
Actually if I got redirect on activation.html page I see content of main page (neccessery config) with strange output, but URL-adress still not changed.
Does somebody knows what could it be?