Hello I know you said you have checked the password XXXXX I do want to you to follow these steps please, we are going to change the broadcast (ssid) to something else than the default which can conflict with neighbors. Now when we do this all wireless devices connected will need to reconnect to the new broadcast name(SSID).
1. First thing is we want to log into the router, you can do that by typing http://192.168.1.1 in the address bar in internet explorer and hitting enter
2. It will ask for a username and password XXXXX the username please leave it blank and for the password XXXXX type admin then hit ok. If that fails please try admin for the username and maybe a password XXXXX you have for the password.
3. Once you are in the router please click on WIRELESS, then click on WIRELESS SECURITY when you are in WIRELESS SECURITY you will notice that it shows a PASSPHRASE? if so that is network password XXXXX make sure that is what you were using before that could be problem to your original problem right there, it is case sensitive. If there isnt a passphrase it might have a KEY then use the first KEY in the list.
4. Now lets click on "BASIC WIRELESS SETTINGS" in there you will notice that it says "Network Name(ssid)" That migth say "Linksys" lets change it to something like linksys44 now once that is changed please click save settings. If you dont see that make sure the configration view is on manual.
5. Now once that is done all wireles devices need to rescan and try to connect to the new ssid name us created in step 4 and also use the password XXXXX you found in step 3. Thsi should sovle your problem.
If this answered your question or got your systems back working please ACCEPT this answer. Thanks!