Re: [12000 GH/s] Slush's Pool (mining.bitcoin.cz); TX FEES + UserDiff; ASIC tested
2 invalid blocks in a row 
19659 2013-08-18 00:43:31 0:24:25 12918777 3385 0.00626088 252722 25.00000000 invalid
19658 2013-08-18 00:19:06 0:41:44 21756147 5705 0.00652499 252730 25.44870012 invalid
19659 2013-08-18 00:43:31 0:24:25 12918777 3385 0.00626088 252722 25.00000000 invalid
19658 2013-08-18 00:19:06 0:41:44 21756147 5705 0.00652499 252730 25.44870012 invalid
252730 is reported as valid on Blockchain and attributed to Slush. Hopefully Slush will fix this one. The 252722 is defo a weird late one, and not found on Blockchain.
How does and Orphaned block happen?