The EA Support forums (thanks Ant and Command and Conquer DEN) have an update on problems owners of the new Kane's Wrath expansion for Command & Conquer 3 are experiencing in online play, as the RTS add-on doesn't always know whether to desync or swim:

Alright, we fully understand the severity of this issue and have our development team all over it trying to figure out what is causing the rampant desyncs some of you may be experiencing. Please understand that tracking down a desync is incredibly challenging.

Since early last week we have been working with the mods and others internally via replays, any substantial data evidence, our customer support department, the technical forums, everything you can imagine to try and repro the desyncs from what people are saying.

We have some very good leads now on what it may be and as soon as I know we have an internal fix in place, i'll let you guys know what the plan to patch will be.

Please understand, we have all hands on deck trying to assess the situation. Any exact evidence you may be able to provide or links to replays would be very helpful as always.

We know if people are using any kind of hacks or trainers, that can desync the game, but we agree that is likely not the main culprit here. So, if you have any exact evidence as to when the game desyncs for you, please feel free to keep providing.

We know about the apparent "8 second" mark and are looking to see if there is any connection there as well.

Overall, we are fully on this and working hard to figure out what is going on.

Please do keep enjoying playing Kane's Wrath online, this issue can certainly be avoided in most games, but we understand its severity.

More soon