World's seed changed?

hello, I've recently noticed a strange problem on my server. Parts of the world that were a certain biome when they were generated, are now a completely different biome. I know because we have a plugin that shows the name of the biome the player is currently in, and it rains in places that should have snow, and sometimes snows in places that should have rain. Also, I've noticed huge totally flat walls that have completely different terrain on either sides. It's almost as if the world's seed was changed, which could explain the flat walls and screwed-up biomes. Does anyone know the cause of this? Is there any possible way to fix the biomes? Thanks.

Oh, and we use TCAdmin with our server, and currently have b860. I have no idea what build we had when the problem started.
Our plugins are:

AppleTreePlugin
BigBrother
Citizens
ControllerBlock
Elevators
Essentials
EssentialsChat
EssentialsSpawn
FenceStack
Gastronomic
GastronomicWater
GeoCacher
iConomy
Locker
MagicCarpet
Movecraft
Permissions
PorteCoulissante
SimpleSpleef
Stargate
ThisBiome
Turnstile
War
WeatherGod
WorldEdit
We also had Multiverse and Towny when the problem started

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

I have same problem, need help aswell!

 

Same issue here it seems like my current seed and original seed are messed up. I get biomes in the wrong places (snow in desert rain in old snow areas etc...) and worldedit's regen doesn't work right as the new chunks it generates are wrong (forests in desert or mountains in flatlands etc...) Anyone know of a way to fix this?

you can see some of this from our dynmap:

http://mc.bongaming.com/maps/#

 

I had the same, but I regened my whole world (whatever).

 

I had done that once, and it's happened again. I'd really rather not put my players through another migration if at all possible.