not converting ÷ to � in some system with internet browsert

not converting ÷ to � in some system with internet browsert

we are using flash file to create questions and user input is pass into
our asp .net web page by calling external javascript method. example user
has entered the input string as "7 × 8 ÷ 9" and click on flash file submit
button the external javascript method is called and string is passed in to
webpage is as same as entered in flash file "7 × 8 ÷ 9". in most of all
system with all browser works fine, but one particular system in IE
browser returning string as "7 × 8 Õ 9" (Unicode UTF 8 format) other
browsers are working fine in this system .
Operating System: Windows 8 (The same OS installed in other system also
works fine) Internet Explorer: IE 10 (version 10.0.9200.16618) the some IE
version work in other system
Please suggest any specific system configuration required to work Unicode
UTF 8 format or required any Unicode font's to install for the system
Thank you in advance