Airport network password changed?

I did a search and didn't come up with anything, so I apologize in advance if this has been previously addressed. I own a G4 Powerbook running Tiger. Yesterday I came home from work, went on the internet, everything was fine. When I woke up i tried to get on the internet and I have no connection. I clicked the airport icon on the menu bar and my network (which I named Jadekitty) wasn't listed. So I then went into System Preferances>Network>Airport>Configure. Listed in the available networks is Jadekitty. So I double-click it and it says

Network Name - Jadekitty
Wireless Security - WEP Password
Password - *********************

The problem is the password isn't what I had chosen a long time ago. It is 3 times longer and not even close to my password. Before I did the above I had attempted to connect to the internet by clicking the airport icon on the menu bar and chosing "Other", then typing in my network name and password, and was then greeted with the window that says "There was an error joining the Airport network." After being confronted with this I went into my Keychain Access, and when trying to get access to the password that Keychain says is my (network)password it will not allow me access to it, saying my Keychain password is invalid. This password allows me access to all other keychains but this one. I have the same password for EVERYTHING (I know some strongly recommend that you don't do that) so I am confounded by this. Upon having this trouble, I went into System Prefs (as stated above) and was very perplexed to see that my password (to join my Jadekitty network)had been changed somehow! Here's the kicker- when seeing the password had been changed, I copied and pasted it and tried to connect that way. I still can't connect to the internet.

I have had this trouble in the past and the only way I could get out of it was to reinstall the OS, which I shouldn't have to do, and I'm sure there was an easier fix but I didn't know where to begin. No one has access to my mac other than my room-mate, and he wouldn't even know how to change anything on my system, nor would he. I don't know how it is possible for my Network password to change itself, but I know I didn't. Can anyone offer any type of explanation for what is happening here? And what on earth can I do to
A) Fix this problem
and
B) Keep it from happening again?

I appreciate any help anyone can offer and thank you in advance.

 

The password I chose is the password I chose. Never have I heard of having to enter a different one...encryption just hides it so other people can't see what you actually chose,or so I thought. I've never been aware that you should have to enter the encrypted version. And if that is the case, I tried that, by entering what my System Prefs said was my password...I copied and pasted, I manually typed, etc. No go. The password for my network is in my keychain, yet that one password I cannot obtain, keychain keeps saying wrong password. Yet I can access all the other keychains with the same password. And anyway, the big question is why did my Jadekitty network vanish from the list? Why when I manually try to join it is it telling my password is false? There is no possability that I "forgot" the password, as I've said it is the same for everything. And out of the blue this problem develops. I didn't install any new software or perform any updates, nor did I change any settings. Once set to "automatically join your preferred network" you should be able to set it and forget it. It was working fine before I went to sleep the other day. No one can offer some type of explanation?