Remove unwanted plain pages

Question

I can't explain why but after some subsections or tables (?), I get a plain page. Here is an example: Between the first and the second table, a plain page is inserted (as well as after the second table). But there are also tables (smaller or bigger doesn't matter) with no plain pages between them. So I don't really understand what is happening here. Btw: the document class is a costum one derived from "article" I think. Any ideas?

Tex. file:

\documentclass[envcountsame,envcountchap, deutsch]{i-studis}
\usepackage{enumitem}
\usepackage{makeidx}
\usepackage{multicol} 
\usepackage[pdftex]{graphicx}
\usepackage[pdftex,plainpages=false]{hyperref}
\usepackage{color}
\usepackage{float} 
\restylefloat{table}
\usepackage[english, ngerman]{babel}
\usepackage[latin1]{inputenc}
\usepackage{textcomp}           
\usepackage{amssymb,amsfonts,amstext,amsmath}   
\usepackage[german, ruled, vlined]{algorithm2e}
\usepackage[a4paper]{geometry}
\usepackage{bibgerm}
\usepackage{array}
\setlength{\textheight}{1.1\textheight}
\pagestyle{myheadings} 
\makeindex 

\begin{document}
\title{Title}
\subtitle{Subtitle}
\project{Project Name}
\supervisor{Prof xy}    
\author{Mackie}                     
\address{City,} 
\submitdate{Date}   
\begingroup
  \renewcommand{\thepage}{Title}
  \mytitlepage
  \newpage
\endgroup

\frontmatter 
\tableofcontents                        
\mainmatter        
\input{chapters/Kapitel_Anforderungen}
\backmatter  
\bibliographystyle{geralpha}
\bibliography{literatur}            
\printindex 
\end{document}

The affected chapter:

\chapter{Anforderungen}

\section{Section 1}

\subsection{Name of subsection}

\def\arraystretch{1.5}
\setlength\tabcolsep{3pt}

\begin{table}[H]
    \begin{tabular}{| p{4.5cm} | p{9.5cm} |}
        \hline
        \textbf{ID} & Anf\_1 \\
        \hline
        \textbf{Bezeichnung} & Lorem ipsum dolor sit amet \\
        \hline
        \textbf{Kurzbeschreibung} & Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor \\
        \hline
        \textbf{Beschreibung} & Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit \\
        \hline
        \textbf{Begründung} & Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam \\
        \hline
        \textbf{Typ } & Lorem ipsum dolor sit \\
        \hline
        \textbf{Abgeleitet von} & - \\
        \hline
        \textbf{Unteranforderungen} & Anf\_1.1, Anf\_1.2, Anf\_1.3 \\
        \hline
        \textbf{Abhängigkeiten} & - \\
        \hline
        \textbf{Quelle} & Prof. xy \\
        \hline
        \textbf{Verantwortlicher} & Some name \\
        \hline
        \textbf{Wichtigkeit} & Verpflichtend \\
        \hline
        \textbf{Referenzen} & \cite{Sae:14} \\
        \hline
        \textbf{Nachweis} & Lorem ipsum dolor sit \\
        \hline
        \textbf{Status} & Akzeptiert \\
        \hline
        \textbf{Kommentar zu Status} & - \\
        \hline
    \end{tabular}
\end{table}

\subsection{Name of subsection 2}

\begin{table}[H]
    \begin{tabular}{| p{4.5cm} | p{9.5cm} |}
        \hline
        \textbf{ID} & Anf\_1.1 \\
        \hline
        \textbf{Bezeichnung} & Lorem ipsum dolor sit amet consetetur \\
        \hline
        \textbf{Kurzbeschreibung} & Lorem ipsum dolor sit amet consetetur \\
        \hline
        \textbf{Beschreibung} & Lorem ipsum dolor sit amet consetetur:
        \begin{itemize}
        \item Level 0: manuelles Fahren/keine Automatisierung
        \item Level 1: sadipscing (\hyperref[sec:acc]{Anf\_1.1.1})
        \item Level 2: elitr, sed diam (\hyperref[sec:spurhalte]{Anf\_1.1.2}) unonumy eirmod (\hyperref[sec:spurwechsel]{Anf\_1.1.3}
        \item Level 3: tempor invidunt ut labore (dolore \hyperref[sec:man]{Anf\_1.1.4})
        \end{itemize}
        dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est 
        \\
        \hline
        \textbf{Begründung} & Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam
        \\
        \hline
        \textbf{Typ} & Lorem ipsum dolor sit amet \\
        \hline
        \textbf{Abgeleitet von} & Anf\_1 \\
        \hline
        \textbf{Unteranforderungen} & Anf\_1.1.1, Anf\_1.1.2, Anf\_1.1.3, Anf\_1.1.4 \\
        \hline
        \textbf{Abhängigkeiten} & - \\
        \hline
        \textbf{Quelle} & Prof. xy \\
        \hline
        \textbf{Verantwortlicher} & Some name \\
        \hline
        \textbf{Wichtigkeit} & Verpflichtend \\
        \hline
        \textbf{Referenzen} & \cite{Sae:14} \\
        \hline
        \textbf{Nachweis} & Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et \\
        \hline
        \textbf{Status} & Akzeptiert \\
        \hline
        \textbf{Kommentar zu Status} & - \\
        \hline
    \end{tabular}
\end{table}

Answer 1

It turned out that the plain pages disappeared, when I split the second table, that was too long apparently. So I just ended the table environment somewhere:

...
\end{tabular}
\end{table}

\begin{table}[H]
\begin{tabular}{| p{4.5cm} | p{9.5cm} |}
...

But I still don't understand why a plain page was inserted before the long table. Well but after four days, I am not expecting any help anymore...