&gt; The root cause appears to have been a switch that was corrupting packets. ... The hypothesis is that occasionally the corrupt packets had valid TCP and Ethernet checksums. One &quot;lucky&quot; packet stored corrupt data in memcache.<p>Did the server (both source and destination) in question both&#x2F;all have ECC-protected memory?  Hopefully that&#x27;s a foregone conclusion but that&#x27;s another big opportunity for errors.