Anyone know why coins I sent to Poloniex still have 0 confirmations?
I sent them from the old MTC-qt as I didn't realize the wallet had been updated.
I am now using the updated version, the transaction is still in my history but it still has 0 confirmations after half an hour

I did the same thing.
I'm a bit paranoid with new exchanges, so I just sent a small amount of 10 MTC (MTS or whatever) to Poloniex
it confirmed ok so I sent another 250 40 min later, still no confirmations after 8 hours.
No biggie really, that's just the price you pay when dealing with obscure altcoins/exchangers
my case also. last night i sent 4 mts to poloniex, 0 confirmations. in the meantime got paid several times during the night from ypool.
this morning i did a test sending 0.001 mts to another of my addresses and same thing. 0 confirmations. the network is working because i received.
problem is in sending.
tnxid aren't even showing up on block crawler.