I've just got the freeze with flashing caps lock/num lock. To reboot I needed to use power button so was quite serious... :/ I haven't seen any particular reason or thing in the logs. I just get this sort of messages all the time (messaes, syslog, kern.log):

Nov 10 15:51:21 newdumolap kernel: [  505.625162] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=202.71.128.65 DST=192.168.1.3 LEN=95 TOS=0x00 PREC=0x00 TTL=107 ID=61278 PROTO=UDP SPT=10646 DPT=55575 LEN=75 
Nov 10 15:51:21 newdumolap kernel: [  505.770846] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=137.222.10.55 DST=192.168.1.3 LEN=413 TOS=0x00 PREC=0x00 TTL=48 ID=44345 DF PROTO=TCP SPT=993 DPT=46920 WINDOW=49680 RES=0x00 ACK PSH URGP=0 
Nov 10 15:51:27 newdumolap kernel: [  512.176301] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=89.77.212.69 DST=192.168.1.3 LEN=1500 TOS=0x00 PREC=0x00 TTL=49 ID=16264 DF PROTO=TCP SPT=51413 DPT=52243 WINDOW=65535 RES=0x00 ACK URGP=0 
Nov 10 15:51:30 newdumolap kernel: [  514.612723] Inbound IN=wlan0 OUT= MAC= SRC=192.168.1.3 DST=239.192.152.143 LEN=147 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=UDP SPT=44287 DPT=6771 LEN=127 
Nov 10 15:51:30 newdumolap kernel: [  514.869275] Inbound IN=wlan0 OUT= MAC= SRC=192.168.1.3 DST=239.192.152.143 LEN=147 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=UDP SPT=44287 DPT=6771 LEN=127 
Nov 10 15:51:30 newdumolap kernel: [  515.371863] Inbound IN=wlan0 OUT= MAC= SRC=192.168.1.3 DST=239.192.152.143 LEN=147 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=UDP SPT=44287 DPT=6771 LEN=127 
Nov 10 15:51:31 newdumolap kernel: [  516.130154] Inbound IN=wlan0 OUT= MAC= SRC=192.168.1.3 DST=239.192.152.143 LEN=147 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=UDP SPT=44287 DPT=6771 LEN=127 
Nov 10 15:51:32 newdumolap kernel: [  517.133522] Inbound IN=wlan0 OUT= MAC= SRC=192.168.1.3 DST=239.192.152.143 LEN=147 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=UDP SPT=44287 DPT=6771 LEN=127 
Nov 10 15:51:59 newdumolap kernel: [  543.982282] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=203.219.128.249 DST=192.168.1.3 LEN=1492 TOS=0x00 PREC=0x00 TTL=110 ID=27805 DF PROTO=TCP SPT=22585 DPT=60695 WINDOW=64816 RES=0x00 ACK URGP=0 
Nov 10 15:52:21 newdumolap kernel: [  565.768684] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=137.222.10.55 DST=192.168.1.3 LEN=413 TOS=0x00 PREC=0x00 TTL=48 ID=38809 DF PROTO=TCP SPT=993 DPT=46920 WINDOW=49680 RES=0x00 ACK PSH URGP=0 
Nov 10 15:52:25 newdumolap kernel: [  569.521948] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=74.192.8.134 DST=192.168.1.3 LEN=1500 TOS=0x00 PREC=0x00 TTL=44 ID=24899 DF PROTO=TCP SPT=8080 DPT=59175 WINDOW=65535 RES=0x00 ACK URGP=0 
Nov 10 15:52:25 newdumolap kernel: [  570.454386] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=85.225.63.54 DST=192.168.1.3 LEN=43 TOS=0x00 PREC=0x40 TTL=49 ID=40900 DF PROTO=TCP SPT=6881 DPT=37173 WINDOW=23067 RES=0x00 ACK PSH URGP=0 
Nov 10 15:52:26 newdumolap kernel: [  570.536133] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=72.177.235.169 DST=192.168.1.3 LEN=231 TOS=0x00 PREC=0x00 TTL=43 ID=54618 DF PROTO=TCP SPT=6881 DPT=35901 WINDOW=20368 RES=0x00 ACK PSH URGP=0 
Nov 10 15:53:21 newdumolap kernel: [  625.769460] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=137.222.10.55 DST=192.168.1.3 LEN=413 TOS=0x00 PREC=0x00 TTL=48 ID=33273 DF PROTO=TCP SPT=993 DPT=46920 WINDOW=49680 RES=0x00 ACK PSH URGP=0 
Nov 10 15:53:31 newdumolap kernel: [  635.999212] Inbound IN=wlan0 OUT= MAC=00:16:ea:d1:ba:c6:00:1e:2a:61:af:e8:08:00 SRC=82.131.136.3 DST=192.168.1.3 LEN=95 TOS=0x00 PREC=0x00 TTL=114 ID=14179 PROTO=UDP SPT=30885 DPT=55575 LEN=75 

Doesn't look like a bug but why it is logged? IMHO, it doesn't look like a necessary message to log - it makes the logs artificially grow.