It is hard to help without seeing the code you use, but it looks like a combination of the twocolumn-option and the multicols environment.
Example:
\documentclass[twocolumn]{article}
\usepackage[utf8]{inputenc}
\usepackage{multicol}
\usepackage{blindtext}
\begin{document}
\blindtext
\begin{multicols}{2}%Here you define a twocolumn-environment inside one columns
\blindtext
\end{multicols}
\blindtext
\end{document}
You have two columns and inside one of this columns you add the multicols-environment. This may be the source of your problem.
Depending on what you need you may
- Don't use the twocolumn option at all.
- switch to one note layout for some pages (
\onenote
command followed by a \twocolumn
-command to switch back). (Attention: This forces page breaks)
- Use the
table*
-environment to span the tabular over two columns (The star * is the important thing!)