Unfortunately, it is time for an update.

Having succesfully updated to v7, I am still experiencing system freezes that drive me nuts.

I looked in the dmesg.2 logfiles from the downloads I took after reboot, and in 2 out of 3 cases, no notification of any error was found.
The last time, a reference is made to the onboard SATA controller:

[ 663.417882] ata1: exception Emask 0x10 SAct 0x0 SErr 0x4000000 action 0xe frozen
[ 663.417885] ata1: irq_stat 0x00000040, connection status changed
[ 663.417887] ata1: SError: { DevExch }
[ 663.417893] ata1: hard resetting link
[ 664.165187] ata1: SATA link down (SStatus 0 SControl 300)
[ 664.185147] ata1: EH complete
[ 899.498772] ata1: exception Emask 0x10 SAct 0x0 SErr 0x4000000 action 0xe frozen
[ 899.498776] ata1: irq_stat 0x00000040, connection status changed
[ 899.498779] ata1: SError: { DevExch }
[ 899.498787] ata1: hard resetting link

However, no disk is connected to that port (only a single SSD on ata2), as can also be seen in earlier in the same logfile:

5.547281] NET: Registered protocol family 5
[ 5.638323] RPC: Registered rdma transport module.
[ 5.907834] ata1: SATA link down (SStatus 0 SControl 300)
[ 6.297160] ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[ 6.298030] ata2.00: ACPI cmd ef/10:06:00:00:00:00 (SET FEATURES) succeeded
[ 6.298033] ata2.00: ACPI cmd f5/00:00:00:00:00:00 (SECURITY FREEZE LOCK) filtered out
[ 6.298035] ata2.00: ACPI cmd b1/c1:00:00:00:00:00 (DEVICE CONFIGURATION OVERLAY) filtered out
[ 6.298566] ata2.00: ATA-9: OCZ-VERTEX4, 1.5, max UDMA/133
[ 6.298569] ata2.00: 500118192 sectors, multi 16: LBA48 NCQ (depth 31/32), AA
[ 6.299425] ata2.00: ACPI cmd ef/10:06:00:00:00:00 (SET FEATURES) succeeded
[ 6.299427] ata2.00: ACPI cmd f5/00:00:00:00:00:00 (SECURITY FREEZE LOCK) filtered out
[ 6.299429] ata2.00: ACPI cmd b1/c1:00:00:00:00:00 (DEVICE CONFIGURATION OVERLAY) filtered out
[ 6.299968] ata2.00: configured for UDMA/133

After experiencing issues with another SSD (previously attached to ata1), I replaced almost all hardware and replaced the SSD with the one that is now attached to ata2.
The SSD is used as an iSCSI target (file i/o) and hosts a Windows 2012 VM (vSphere) with a small SQL 2012 database.

Strangely enough, I've ran this exact config for over 2 years without any problem, until 2 months ago.
Is there anyone that has a clue?