Well maybe once per 3 transactions I get a stuck one. Meaning the transaction is no where to be found on blockchain.info and stays at 0 confirmations in the client for ever.
Clear All Unconfirmed works great and then it goes out just fine but I thought you might find it useful to know that it happens quite often.
That's with the latest version (was same with older versions actually) on Linux.
Have you set your minimum fee to 0? And how fast do you emit these transactions?
No, the fee is the default one. I'm not sure how I can measure how fast I emit them. I just send them.
I'll submit bug report next time it happens