When you do get a connection, how strong is the signal. If it's very weak (but your other devices can connect with no issues), then can you maintain a strong connection at another location (eg office, friend's place, or a public wifi hotspot). If you're getting a weak signal everywhere and dropping connections then it's likely to be a hardware issue.
On the other hand, if your signal is strong at home, and you can maintain a connection elsewhere, then it could be an interference issue within your home. Interference can be caused by a whole number of things including cordless phones, AV transmitters and even microwaves. Keep in mind that interference can affect different devices differently. For example you might have two identical laptops sitting next to each other, and one can be affected whilst the other isn't.
If it is this second case of potential interference, then post back and will give you a few tips on how you could improve situation