What does "PROOF OF WORK RESULT: false (booooo)" mean when mining? I'm mining (Litecoin miner, shouldn't matter) with minerd, and got this in the output:

[2011-10-13 07:12:02] thread 1: 5524 hashes, 0.96 khash/sec
[2011-10-13 07:12:02] thread 0: 5415 hashes, 0.95 khash/sec
[2011-10-13 07:12:04] thread 0: 1588 hashes, 0.94 khash/sec
[2011-10-13 07:12:04] PROOF OF WORK RESULT: false (booooo)
[2011-10-13 07:12:04] thread 6: 5319 hashes, 0.95 khash/sec
[2011-10-13 07:12:04] thread 5: 6026 hashes, 0.96 khash/sec


What does the "Proof of work result: false" mean? Is it a stale block, meaning a block I just solved, but someone else beat me to it and published it first?
You're solo mining. So there's nothing useful you can do with a share -- there's nothing for you to share in. Every share you find will be rejected, unless you actually mine a block.