I have been experiencing the same problem: freezing almost every day or every week. Running Debian Jessie Vanilla with SSD. I have even upgraded my power supply to a full ATX (PC) power supply, and LiPo battery, but still freezing. I checked the power demand with a digital multimeter in MIN/MAX mode and the current never went above 500mA. I doubt this is a power issue, and if it is, it is on the board, not the external power supply.
I also see a lot of ATA errors in /var/log/syslog:
[ 753.731120] ata1.00: exception Emask 0x0 SAct 0x600 SErr 0x0 action 0x0
[ 753.731144] ata1.00: irq_stat 0x40000000
[ 753.731161] ata1.00: failed command: READ FPDMA QUEUED
[ 753.731184] ata1.00: cmd 60/08:48:20:cf:f4/00:00:24:00:00/40 tag 9 ncq 4096 in
res 41/04:08:20:cf:f4/00:00:24:00:00/00 Emask 0x401 (device error) <F>
[ 753.731196] ata1.00: status: { DRDY ERR }
[ 753.731203] ata1.00: error: { ABRT }
[ 753.731212] ata1.00: failed command: READ FPDMA QUEUED
[ 753.731232] ata1.00: cmd 60/08:50:28:1e:c0/00:00:24:00:00/40 tag 10 ncq 4096 in
res 41/04:00:20:cf:f4/00:00:24:00:00/40 Emask 0x1 (device error)
[ 753.731242] ata1.00: status: { DRDY ERR }
[ 753.731249] ata1.00: error: { ABRT }
[ 753.731552] ata1.00: supports DRM functions and may not be fully accessible
[ 753.732143] ata1.00: supports DRM functions and may not be fully accessible
[ 753.732397] ata1.00: configured for UDMA/133
[ 753.732500] sd 0:0:0:0: [sda] tag#10 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x08
[ 753.732519] sd 0:0:0:0: [sda] tag#10 Sense Key : 0x5 [current] [descriptor]
[ 753.732532] sd 0:0:0:0: [sda] tag#10 ASC=0x21 ASCQ=0x4
[ 753.732552] sd 0:0:0:0: [sda] tag#10 CDB: opcode=0x28 28 00 24 c0 1e 28 00 00 08 00
[ 753.732563] blk_update_request: I/O error, dev sda, sector 616570408
[ 753.732615] ata1: EH complete
Do any of you see ATA erros in syslog? I do not know if this is related to the freezing problem. I have tried other SATA cable, but same result.
Today, I was monitoring /var/log/syslog and I saw litteraly multiple pages of logs dumping on the HDMI screen because of a crash. I was able to take a picture of the last screen, see http://imgur.com/37ZXssp.
EDIT 2016-04-01, extra info:
I am running ARMBIAN Debian GNU/Linux 8 (jessie) 4.4.1-sunxi
rootfs on uSD card, SSD only holds extra data in ext4
I have changed the governor to performance and no problems yet. No SATA errors in syslog, no craches.