Cannot connect 2 x windows 7 homepremium 64 PCs in Homegroup

Cannot connect 2 x windows 7 homepremium 64 PCs in Homegroup

i just swapped the motherboard on my spare computer and did a fresh windows 7 install with Homepremuim 64 sp1 now i cannot connect to homegroup both computers are connected to internet via wireless through my router but will not connect to homegroup

ive tried dissolving my homegroup and starting a new one, no luck
tried starting homegroup on spare with new install and tried to join my main , no luck

computers were connected just fine prior to mobo swap and fresh install

all media streaming settings on for both units and homegroup troubleshooter finds no errors.

any ideas appreciated

had to disable the network bridge on my main and reconnect using the wireless adapter before i could join homegroup.