After the update I quickly realized that both FireFox and Opera rendered the web management interface incorrectly. I sat down with their online support (full transcript here) that and concluded that they had no support for other browsers than Internet Explorer (surprise...) and they failed to give me the older firmware which worked fine.
They even agreed on that the only option for me to access the management was to purchase a Microsoft Windows licence.
The web browser support would not have been a problem if they would have included featurability and configuration options through their serial CLI menu interface. Though the CLI is designed only to support dummy L2 (No VLAN/SNMP/ACLs/QoS etc) switching functionality options.
I have verified that this is the case with their 48 port gigabit ethernet switch aswell.
I'm posting this article primarily to discourage users in the same situation as me from using their product and secondarily to send a message to management of LinkSys to work towards supporting open platforms for atleast products such as switches. If it's by improving their CLI or making their web interface more compatible would both be a satisfactory solution."