Can't connect to wireless networks with passwords

Hello, I'm fairly new to macs (got one last year for school) and when I first got it I was able to use wireless internet fine. However, since an update I haven't been able to connect to wireless networks at home when I put a password on ours. Actually, it connects after a while but after a few minutes I lose the connection, though the mac seems to think I'm still connected. The PC connects fine but because of my MacBook we are forced to leave the password off. Is there any solution to this?