Mac Pro randomly disconnecting USB devices

Hello All,

Am hoping someone out there will be able to advise me. I have a 1TB external SATA drive connected directly to one of my Mac Pro USB ports, (that is, not via a USB hub). The Mac Pro has a habit of randomly disconnecting the drive during file transfers. It seems to particularly do it when the screen saver initiates itself. I've disabled the screen saver but unfortunately that hasn't resolved the problem. The problem itself doesn't seem to be isolated to the external USB hard drive either. The Mac has on occasions disconnected other USB devices too.

Any suggestions or ideas on what the cause of it is and how I resolve it?

Many thanks

GPJ007

Mac OS X (10.6.5)

Posted on Jun 3, 2011 10:38 AM

Feb 26, 2012 8:14 AM in response to habster81

Still had the Problem with all USBports on my MacPro, the slots on the PCI-E Card work so far.

Today I had time to reinstall the OS and were looking foreward to solve this problem with that action...

Well it didn't worked, or just half half... After a totaly new installation the OS was stable and all USB ports worked well. Then I updated the OS to the newest status and there was the issue again... !! ? all HDD's that were conneted to the MacPro's USB slots started to disconnect as soon as I tried to access any data.. or somethimes just because of ??? ...who knows.. 🙂

Finally I found this discussion and followed more or less the instructions.
https://discussions.apple.com/thread/2644159?start=0&tstart=0

Just that I used the .kext from the install disc and not the one of the 10.6.8 update.

The first restart just came to a blue screen.. then I restarted again and since then the problem is gone..

This worked for me, hopefully also for others