Vista Business losing internet connectivity

Hi,

I am using Vista Business and at least once a day I lose my connection
to the internet.

BUT....

We are on a LAN and all other clients can see the the Net when my
connection fails.

I can still use the LAN so the problem is not with the network
hardware of the machine or switch(just in case I have tried several
cards but it still behaves the same.)

There is no problem with filtering on the router (we dont use MAC
filtering or IP filtering).

Anyone else experienced this? The only solution is to restart the PC.