Boot from external SSD cause freeze

Question

I bought a Samsung 830 SSD ( 256 GB model MZ-7PC256D )
I planned to connect it to my 27" 3.5 GHz Intel i7 iMac (mid 2011) via thunderbolt with the Seagate GoFlex adapter and use it as primary boot drive.
I installed Lion (I'm running OS X 10.7.5) on the new external drive using the OS X Recovery.
Everything runs fine and very fast except that system randomly freeze.
I can't open/close apps and the spinning beachball appears. I can't do anything other than power-off holding down the power button.
I disabled the "disk sleep" option, disk seems ok (I checked the status and said verified) but system keeps freezing.
It appears that after the first freeze, soon occur a second one.
Also, I noticed strange(?) sound (something like tock) from the adapter/SSD during the normal use.
I searched for the word error in the Console at the corresponding freeze time and this strings came out:
17/12/12 18:04:06,000 kernel: SMC::smcInitHelper ERROR: MMIO regMap == NULL - fall back to old SMC mode
17/12/12 18:04:09,043 WindowServer: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
17/12/12 18:04:09,888 Finder: kCGErrorIllegalArgument: _CGSFindSharedWindow: WID 31
17/12/12 18:04:09,888 Finder: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
17/12/12 18:04:09,888 Finder: kCGErrorIllegalArgument: CGSRemoveSurface: Invalid window 0x1f
17/12/12 18:04:17,891 talagent: CGSConnectionRelinquishWindowRights(cid, newWindowNumber, reservedRights): CGError 1001 on line 619
17/12/12 18:04:17,891 talagent: CGSReleaseWindow(cid, wid): CGError 1001 on line 759
[Here the complete error log]
Any suggest?

Answer 1

I'm not certain this is the culprit, but the overall consensus that I've read online points to the fact that most (or all?) available external Thunderbolt drive enclosures that are *bus-powered only* (so no independent power brick with the enclosure) have difficulty providing enough power to SSD's that exceed ~240GB. And without enough power the system freezes or causes other errors.
Here's at least one thorough examination that came to this conclusion:
http://wolfgangtechnology.blogspot.com/2012/06/mac-with-seagate-thunderbolt-adap ter.html
The solution, from what I've read at least, is to find a Thunderbolt adapter with an independent power source or use a smaller SSD (under 240GB it seems) that is capable of running on bus-power only.
I'm looking into doing the same as you (using external SSD as primary boot drive) but there aren't that many relatively-affordable enclosures to choose from at this point (off the top of my head just the Seagate GoFlex, Buffalo Ministation, and Lacie offerings come to mind) and there's still an outstanding question as to whether the available enclosures support the SATA III spec to really get the most out of the fastest SSD's available today.
Of note, I believe this version of Seagate's adapter (the "Desktop" version) does come with its own power brick and could solve your problem, at least according to the article I linked above.
Hope this helps, good luck!