I see these around 15 to 20 days of uptime.  This is the 1.6 release

panic: fpsave ipi didn't
syncing disks... tlp0: receive ring overrun
tlp0: transmit timeout
tlp0: filter setup and transmit timeout
tlp0: filter setup and transmit timeout
tlp0: filter setup and transmit timeout
tlp0: filter setup and transmit timeout
tlp0: filter setup and transmit timeout
tlp0: filter setup and transmit timeout
tlp0: filter setup and transmit timeout

It was doing this before with 1.5ZC as well .. After installing 1.6 I
began seeing these as well:

stray kn300 irq 12
stray kn300 irq 12
stray kn300 irq 12
stray kn300 irq 12
stray kn300 irq 12
stray kn300 irq 12
stray kn300 irq 12

This maps to:

isp0 at pci1 dev 3 function 0: QLogic 1020 Ultra Wide SCSI HBA
isp0: interrupting at kn300 irq 12
scsibus0 at isp0: 16 targets, 8 luns per target