Actually Microsoft Word automatically apply some meta tags to the documents which are illegal (not allowed) in Blogger posts. These tags are like these:
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=windows-1252">
<META NAME="Generator" CONTENT="Microsoft Word 97">
To get rid of this error, you can paste your Word document in a simple Notepad, Wordpad or Notepad++ (Recommended) and then copy it again and paste it to Blogger post editor. Then you can continue working with the post and Publish it.
Tip: You can free download Notepad++ from here.