Help wifi problem

[helpmeplz]

hi everybody.
I just got Nexus S a month ago and its my first experience with android.unfortunately I haven't feel good with this OS instead lot of problems.from bluetooth issues(for ex I cant transfer apk files) to wifi problems.
I have an wifi connection in my home that the security type is WPA2/AES . the signal is full,and all goes right.when I trying to connect,first it shows that its authenticating ,then connecting,after all for a few seconds it disconnects automaticly.then again and again this cycle continues . and never connects.
after all,by the name of my connection shows this words:"Disabled"!!!
who disabled that and why ??
I tried Xperia X10(android 2.2 I think).nor my Nexus neither X10 connects and have a same problem.but other phones like Vivaz(symbian OS) do not have any problems with this network.
plz help me if you can so I'll be so thankful
HELP MEEEE HEEEEEEEELP! (

 

[RavenFox]

*Try turning your modem and router off and on [about 10seconds off]
*If you have a N router try turning off the N option and just let B&G broadcast
*Make sure you are using the exact router authentication phrase
*Another option if all else fails is to use TKIP instead of AES. TKIP is less secure but unless your guarding fighter jet secrets I don't think the individuals capable of cracking that will be knocking on your firewall.