Currently Being ModeratedJun 1, 2012 10:21 AM (in response to Event Video Guy)
The USB ports are designed to output a maximum of 500 milliamps. It may be that the HDDs that you are using exceed that threshold. Try using a powered hub for that port and see if that solves that problem. If it does not, the the Apple store genius bar should be the place to have the problem diagnosed.
Currently Being ModeratedJun 1, 2012 10:32 AM (in response to Event Video Guy)
Exactly what Ogelthorpe mentioned.
I bought a Seagate 500GB 7200RPM and bought an external case from Staples that has a big fancy led to show HD activity. Sometimes it works and sometimes it doesn't.
Tested it on my PC and it works all the time so it got me stumped. Thought it was my MB.
Decided to try another external drive drive on my MB and everything works. So I returned the fancy external enclosure and bought the simple $10 one.
Now everything works fine.
Maybe changing your external case might help you.
Currently Being ModeratedJun 1, 2012 1:42 PM (in response to Event Video Guy)
I have a Seagate Freeagent Goflex 500GB. It one of those small 2.5" hard drives that is powered through the USB cable. But I never had a problem with it for the first year that I used it. Then all of the sudden it began glitching.
Then to test to see if it was the drive, I hooked up my other external hard drive. Now this one is a full sized 3.5" drive. It uses an external power supply. The same thing happens to that one as well.
Currently Being ModeratedJun 1, 2012 3:12 PM (in response to Event Video Guy)
Take your MBP and the HDDs to an Apple Store genius bar and have them check out your problem.