I keep being suspicious of it, but without a bug to paste into, I'm not sure how often. Equal probabilities it's disk, memory, the-whole-thing. In front of me right now, https://tbpl.mozilla.org/php/getParsedLog.php?id=24073560&tree=Mozilla-Inbound is a bad CRC unzipping a test file.
https://tbpl.mozilla.org/php/getParsedLog.php?id=24073420&tree=Mozilla-Beta - bad CRC unzipping symbols. Your release-mozilla-beta 10.6 browser-chrome from this morning? Dunno, but bad CRC wouldn't surprise me.
Disabled on slavealloc. Requesting IT to run diagnostics and re-imaging.
RAM has been replaced. Back in production.
"replaced both memory sticks and reimaged the host." --> rebooted to production