Stylish install Problems with AVG Version 9.0

Am running Stylish Version 1.0.2 in Firefox 3.5.3
Works well.

Have tried to install more recent Versions of Stylish and Stylish refuses to install.

Have Googled the problem.

Have tried disabling AVG Free(Version 9)(recently installed)
Did not work
Have tried loading Firefox in safe mode.
Did not work

Uninstalled AVG Free (Version 9)
Managed to load new Version of Stylish with no problem.

MOST TIRESOME !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!