Gzip Compression

Hi,
to improve the Page Speed figures installed the plugin ‘Gzip Compression’ and now my browser, Firefox, cannot display and gives me this error message:

Content Encoding Error

The page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression.

Please contact the web site owners to inform them of this problem.

Could you help, please?
Thanks,
Susana