Are you using the namecoin main branch from github yet, or is it the old version? I'm about to push the updated namecoind to all my other servers (only running on 2 of 6 pool servers at the moment). I'll take a peek at my logs to see if there's been any noticeable jump in stales for Guild since updating 1/3 the pool to the latest namecoin hardfork version.
I am using the updated version of the original namecoind. It's not related to the update. I've seen this happen a couple times before. Seems to happen about once or twice per year. Usually namecoin was in an abandoned state with no developers, but now it has some, maybe they can figure it out. I sent them some info.
What happens is that namecoind gets into a broken state and I get this in its debug.log at apparently random intervals:
ERROR: ConnectInputsHook() : name_update on an expired name, or there is a pending transaction on the name
ERROR: ConnectInputsHook() : name_update on an expired name, or there is a pending transaction on the name
Here is one block being created. It seems to be propagating to other nodes, but for some reason they don't consider it part of the chain.
SetBestChain: new best=749f8868705d1c3d8313 height=148257 work=14693287269252460633786
ProcessBlock: ACCEPTED
ThreadRPCServer method=getblockcount
ERROR: ConnectInputsHook() : name_update on an expired name, or there is a pending transaction on the name
ERROR: ConnectInputsHook() : name_update on an expired name, or there is a pending transaction on the name
sending: inv (37 bytes) <-- Repeats many times
received: getdata (37 bytes)
received getdata for: block 749f8868705d1c3d8313
sending: block (12655 bytes)
^- repeats the 3 above many times
Could it be related to broken transactions? Maybe my node is creating blocks with invalid transactions and accepting those blocks, while other nodes reject them. At least that is my first guess.