Likewise, I'm on 0.3.22-beta and have come across the 'You must pay a transaction fee' message for the first time.
Whilst I have no objection to paying an appropriate transaction fee, at the current exchange rate, BTC0.01 is USD0.30 which seems an excessive amount in absolute terms (even as 0.5% of the amount I was sending it seems like a large amount anyway).
I appreciate that the current software is a reference client, however, it does confuse the matter by the wording it uses...
"Optional transaction fee per KB ... Most transactions are 1KB ... 0.01 recommended."
Should, perhaps, better be worded:
"Mandatory transaction fee per KB for some transactions ... There's no way of telling in advance which transactions require the fee and we're not going to tell you how big your transaction is ... At least 0.01 required"
In addition, the error dialogue box shows the message:
"Error: This transaction requires a transaction fee of at least 0.01 because of its amount, complexity or use of recently received funds."
Well, which is it?
If it's the recently received funds, how long should I wait? Is it really too difficult to have three messages which either say:
"Error: This transaction requires a transaction fee of at least 0.01 because of its amount.",
"Error: This transaction requires a transaction fee of at least 0.01 because of its complexity.", or
"Error: This transaction requires a transaction fee of at least 0.01 because of its use of recently received funds. Please wait X hours or until Y confirmations have been received."
Note that none of those error conditions tell you the size of the transaction in KB.
Like I said, if a transaction fee is due, then so be it. I'd just like the client to make things clearer to me.
Niccy