Dear Leann,
I got yet another crash today after just a few hours of fresh session. I was using wireless with no encryption.  I do not have ethernet here.
The agonizing kernel  entries of the kernel log are these (followed by the boot messages):
Mar 22 19:12:06 jenshen kernel: [28185.688033] wlan0: associate with AP f61b66a8
Mar 22 19:12:06 jenshen kernel: [28185.689771] wlan0: RX AssocResp from c9ba202a (capab=0x401 status=12 aid=0)
Mar 22 19:12:06 jenshen kernel: [28185.689779] wlan0: AP denied association (code=12)
Mar 22 19:12:06 jenshen kernel: [28185.888048] wlan0: association with AP f61b66a8 timed out
Mar 22 19:12:34 jenshen kernel: [28214.066629] wlan0: authenticate with AP f61b66a8
Mar 22 19:12:34 jenshen kernel: [28214.071865] wlan0: authenticated
Mar 22 19:12:34 jenshen kernel: [28214.071875] wlan0: associate with AP f61b66a8
Mar 22 19:12:34 jenshen kernel: [28214.074175] wlan0: RX AssocResp from f6f8902a (capab=0x401 status=12 aid=0)
Mar 22 19:12:34 jenshen kernel: [28214.074184] wlan0: AP denied association (code=12)
Mar 22 19:12:35 jenshen kernel: [28214.268063] wlan0: associate with AP f61b66a8
Mar 22 19:12:35 jenshen kernel: [28214.269934] wlan0: RX AssocResp from de4cc02a (capab=0x401 status=12 aid=0)
Mar 22 19:12:35 jenshen kernel: [28214.269943] wlan0: AP denied association (code=12)
Mar 22 19:12:35 jenshen kernel: [28214.468612] wlan0: associate with AP f61b66a8
Mar 22 19:12:35 jenshen kernel: [28214.470933] wlan0: RX AssocResp from de4ce02a (capab=0x401 status=12 aid=0)
Mar 22 19:12:35 jenshen kernel: [28214.470942] wlan0: AP denied association (code=12)
Mar 22 19:12:35 jenshen kernel: [28214.668048] wlan0: association with AP f61b66a8 timed out
Mar 22 19:12:38 jenshen kernel: [28217.883610] wlan0: authenticate with AP f61b66a8
Mar 22 19:12:38 jenshen kernel: [28217.883666] wlan0: authenticate with AP f61b66a8
Mar 22 19:12:38 jenshen kernel: [28217.885783] wlan0: authenticated
Mar 22 19:12:38 jenshen kernel: [28217.885791] wlan0: associate with AP f61b66a8
Mar 22 19:12:38 jenshen kernel: [28217.889754] wlan0: RX AssocResp from dfd5202a (capab=0x401 status=0 aid=2)
Mar 22 19:12:38 jenshen kernel: [28217.889762] wlan0: associated
Mar 22 19:15:44 jenshen kernel: [28403.419054] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 19:21:24 jenshen kernel: [28743.435328] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 19:25:24 jenshen kernel: [28983.423238] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 19:29:24 jenshen kernel: [29223.490565] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 19:33:12 jenshen kernel: [29451.473833] ath5k phy0: unsupported jumbo
Mar 22 19:41:24 jenshen kernel: [29943.427415] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 19:45:24 jenshen kernel: [30183.414603] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 19:51:24 jenshen kernel: [30543.431222] ath5k phy0: noise floor calibration timeout (2462MHz)
Mar 22 20:09:25 jenshen kernel: Inspecting /boot/System.map-2.6.28-11-generic
Mar 22 20:09:25 jenshen kernel: Cannot find map file.
Mar 22 20:09:25 jenshen kernel: Loaded 55383 symbols from 43 modules.
Mar 22 20:09:25 jenshen kernel: [    0.000000] BIOS EBDA/lowmem at: 0009dc00/0009dc00
Mar 22 20:09:25 jenshen kernel: [    0.000000] Initializing cgroup subsys cpuset
Mar 22 20:09:25 jenshen kernel: [    0.000000] Initializing cgroup subsys cpu

I might be wrong but a machine with frequent freezes should be called "absolutely unstable and insecure". What else should be done to get some attention? 
Is it possible to use the atheros driver I used to use in intrepid. Or should I downgrade to intrepid, or is it better to install fedora core 10 or get a freebsd?

Please let me know
Thanks in advance