Ex470 Gigabit Issue

HI,

I've got a MSS EX470 (NIC is SiS191)and yesterday I noticed that when you run taskmanager and check under the network tab it says that I only have 100mbit connection.
I've tried the usual (i.e. change cable to cat6, swopped cable to another computer which has 1gbit connection) .
I am sitting on a Dlink DIR655 that is supposed to be a gigabit switch.

Any ideas on how to fix so that I will get gigabit speed in my network?

Thanks!