Could be hardware or software IMO. YOu need to give more details. What hardware do you have, what OS, when did this issue start, did you do anything before this issue, did you just reformat, have you done a virus scan, have you done a spyware scan, have you tried reinstalling the drivers, how is your current network setup, can you connect through any other computers on that same network?
Answer ALL of the above and we can give you more help.