Something fishy here...
Tetcoin developer released a minor update to the wallet no hard forking or consensus change. He blocks older clients from connecting to his new one.
// network protocol versioning
//
-static const int PROTOCOL_VERSION = 70003;
+static const int PROTOCOL_VERSION = 12870003;
// intial proto version, to be increased after version/verack negotiation
-static const int INIT_PROTO_VERSION = 209;
+static const int INIT_PROTO_VERSION = 128209;
// disconnect from peers older than this proto version
-static const int MIN_PEER_PROTO_VERSION = 70003;
+static const int MIN_PEER_PROTO_VERSION = 12870003;
// nTime field added to CAddress, starting with this version;
// if possible, avoid requesting addresses nodes older than this
@@ -42,9 +42,9 @@ static const int NOBLKS_VERSION_START = 32000;
static const int NOBLKS_VERSION_END = 32400;
// BIP 0031, pong message, is enabled for all versions AFTER this one
-static const int BIP0031_VERSION = 60000;
+static const int BIP0031_VERSION = 12860000;
// "mempool" command, enhanced "getdata" behavior starts with this version:
-static const int MEMPOOL_GD_VERSION = 60002;
+static const int MEMPOOL_GD_VERSION = 12860002;
#endif
He fails to mention this on the forum thread. Months go by, several users continue using the 'older' client and now there are two block chains.
2015-01-02 11:26:20 received block 178a051007c33c93cf98ddbe837fe30c1b6b3499f5687f39246be3aa8f46b197
2015-01-02 11:26:20 ERROR: CheckProofOfWork() : hash doesn't match nBits
2015-01-02 11:26:20 ERROR: CheckBlock() : proof of work failed
2015-01-02 11:26:20 ERROR: ProcessBlock() : CheckBlock FAILED
2015-01-02 11:26:20 Misbehaving: 93.118.178.241:59288 (0 -> 50)
2015-01-02 11:26:43 stored orphan tx b620433a2c2db2b7a3ef2caa15b66b071a582a71b432b495de411a5be205f86d (mapsz 10001)
2015-01-02 11:26:43 mapOrphan overflow, removed 1 tx
2015-01-02 11:26:47 stored orphan tx 5089fd1831481bf760827773e563ffc3e934013a534047ecfc9c9e7255953693 (mapsz 10001)
2015-01-02 11:26:47 mapOrphan overflow, removed 1 tx
2015-01-02 11:26:48 received block 26d9dbf22c30cfd05c2f538d2e8709dea2467650d0792c16ba1eaaeee73cc73a
2015-01-02 11:26:48 ERROR: CheckProofOfWork() : hash doesn't match nBits
2015-01-02 11:26:48 ERROR: CheckBlock() : proof of work failed
2015-01-02 11:26:48 ERROR: ProcessBlock() : CheckBlock FAILED
2015-01-02 11:26:48 Misbehaving: 93.118.178.241:59288 (50 -> 100) DISCONNECTING
2015-01-02 11:26:48 disconnecting node 93.118.178.241:59288
2015-01-02 11:26:48 socket select error 9
2015-01-02 11:26:53 stored orphan tx d075597f90dc372d1044929deeb6f9e693f1851f4e5f7f5278f0a6e38748fb22 (mapsz 10001)
2015-01-02 11:26:53 mapOrphan overflow, removed 1 tx
