Has anyone else had issues with the latest versions of FF behaving badly with zimbra?

I am getting more and more uses complaining of not being able to open their attachments with FF unless they fwd them to them selves but on other browsers or even other machines with FF it works fine.

Also now some are getting errors when trying to attach pdf's etc in FF... but again use another browser it doesn't happen.

I am very seriously considering dumping FF and going back to Ie or Chrome as the complaints just aren't stopping.. this has only happened since FF3, and or 5.0.9 of ZCO.

Uninstalling FF and reinstalling it doesn't fix it but a total reinstall of the PC does... odd.