Can't attach file in Internet Explorer 8 & 9

When you try to upload a picture in Internet Explorer 8 you get the following error message:

File name cannot contain the character '\'

We are running JIRA in the internal network and then the Internet Explorer detects it as Intranet site.

The workaround from JRA-31719 works but it is not a good solution

In the IE9 client, disable the "Include local directory path when uploading files to a server". By default this is disabled.

Please try to fix the problem in general.