script errors in IE

I work on extjs-based (v 3.4) website. At Firefox, Safari and Chrome it runs well. But when I try to use Internet Explorer 9 I always get strange errors:

SCRIPT5009: 'п»ї' is undefined 
ext-lang-ru.js, line 7 character 1

SCRI开发者_如何学JAVAPT87: Invalid argument. 
ext-all.js, line 7 character 90121

I tried to save my files in different encodings, but it didn't help. Maybe anyone else had already faced such problem?

Try setting the charset-attribute of the script-file:

<script src="path/to/ext-lang-ru.js" charset="utf-8"></script>