This is designed to speed up the download, but, unfortunately it also compresses already compressed SWF files.
To fix the problem you can either ask your host provider to set the server to not compress the SWF files in your user directory or you can do this yourself by uploading a .htaccess file.
How to make the .htaccess file
- Open a text editor and copy and paste the below in to the page:
SetEnvIfNoCase Request_URI .swf$ no-gzip dont-vary
- Save it as a plain text document using the file name htaccess.txt.
- Upload it to your user directory on the server, then while on the server rename it to .htaccess