My MBP has recently been behaving badly. It started as crashes while asleep with no obvious crash message (i.e. your mac shut down improperly) doesn't require a 10 sec shutdown, a quick press of the power button reboots. I can't see any obvious crashes in the log (but I'm no expert). Tried resetting the PRAM, SMC, energy savings settings. Eventually mac started freezing and an external drive (1 of 2 Seagate go flex thunderbolts) didn't show up anymore. Rebooting with that drive in would result in a frozen system within a minute or two of restarting. RMA'd that drive, but soon after the other drive starting doing the same. RMA'd that one and before I could ship it back, the replacement for the first started doing the same. I've tried running them straight to the second thunderbolt port instead of via thunderbolt display. Checked for new firmware, etc. Is there a way to diagnose or test the thunderbolt bus? I'm hesitant to wipe and reinstall because my Time Machine backup is on the external drive that's now shifty. Pertinent Details: RMBP mid 2012 10.9.4 two segate go flex thunderbolt drives (B dupes A via Superduper when both are working) Thunderbolt Display Any help much appreciated.