I have the same issue, except that it doesn't seem to matter if the computer ever went to sleep.

I am running a PC 1005HA, Ubuntu 9.04, Linux raven 2.6.28-15-generic #49-Ubuntu.

[   21.274268] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   21.274275] Bluetooth: BNEP filters: protocol multicast
[   21.308055] Bridge firewalling registered
[   23.235989] ppdev: user-space parallel port driver
[   23.813689] [drm] Initialized drm 1.1.0 20060810
[   23.846246] pci 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
[   23.846255] pci 0000:00:02.0: setting latency timer to 64
[   23.846582] [drm] Initialized i915 1.6.0 20080730 on minor 0
[   23.851750] [drm:i915_setparam] *ERROR* unknown parameter 4
[   23.851817] [drm:i915_getparam] *ERROR* Unknown parameter 6
[   25.126498] [drm:i915_getparam] *ERROR* Unknown parameter 6
[   26.874978] ADDRCONF(NETDEV_UP): wlan0: link is not ready
[   39.809478] [drm:i915_getparam] *ERROR* Unknown parameter 6
[   42.095204] [drm:i915_getparam] *ERROR* Unknown parameter 6
[   43.768597] wlan0: authenticate with AP f64706b8
[   43.770551] wlan0: authenticated
[   43.770560] wlan0: associate with AP f64706b8
[   43.776342] wlan0: RX AssocResp from f635602a (capab=0x411 status=0 aid=2)
[   43.776353] wlan0: associated
[   43.791028] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   43.887377] cfg80211: Calling CRDA for country: IE
[   43.903943] cfg80211: Current regulatory domain updated by AP to: IE
[   43.903954]  (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp
)
[   43.903962]  (2402000 KHz - 2477000 KHz @ 40000 KHz), (N/A, 2000 mBm)
[   44.144362] padlock: VIA PadLock not detected.
[   54.224048] wlan0: no IPv6 routers present
[   76.220082] wlan0: beacon loss from AP f64706b8 - sending probe request
[   78.220085] wlan0: no probe response from AP f64706b8 - disassociating

...

[ 1520.590103] wlan0: RX ReassocResp from f550e02a (capab=0x411 status=0 aid=2)
[ 1520.590114] wlan0: associated
[ 1936.652180] wlan0: beacon loss from AP f64706b8 - sending probe request
[ 1938.652165] wlan0: no probe response from AP f64706b8 - disassociating
[ 1939.747872] wlan0: authenticate with AP f64706b8
[ 1939.757973] wlan0: authenticate with AP f64706b8
[ 1939.759516] wlan0: authenticated
[ 1939.759525] wlan0: associate with AP f64706b8
[ 1939.766669] wlan0: RX ReassocResp from f56ec02a (capab=0x411 status=0 aid=2)
[ 1939.766680] wlan0: associated
[ 2686.060069] wlan0: beacon loss from AP f64706b8 - sending probe request
[ 2688.060072] wlan0: no probe response from AP f64706b8 - disassociating
[ 2689.155759] wlan0: authenticate with AP f64706b8
[ 2689.165908] wlan0: authenticate with AP f64706b8
[ 2689.168654] wlan0: authenticated
[ 2689.168662] wlan0: associate with AP f64706b8
[ 2689.175090] wlan0: RX ReassocResp from f51aa02a (capab=0x411 status=0 aid=2)
[ 2689.175101] wlan0: associated
[ 2716.020071] wlan0: beacon loss from AP f64706b8 - sending probe request
[ 2718.020079] wlan0: no probe response from AP f64706b8 - disassociating
[ 2719.116942] wlan0: authenticate with AP f64706b8
[ 2719.119013] wlan0: authenticated
[ 2719.119022] wlan0: associate with AP f64706b8
[ 2719.124663] wlan0: RX ReassocResp from f541802a (capab=0x411 status=0 aid=2)
[ 2719.124675] wlan0: associated
[ 3137.540079] wlan0: beacon loss from AP f64706b8 - sending probe request
[ 3139.540074] wlan0: no probe response from AP f64706b8 - disassociating

...

[ 7820.176073] wlan0: no probe response from AP f64706b8 - disassociating
[ 7821.271857] wlan0: authenticate with AP f64706b8
[ 7821.281973] wlan0: authenticate with AP f64706b8
[ 7821.284137] wlan0: authenticated
[ 7821.284148] wlan0: associate with AP f64706b8
[ 7821.292141] wlan0: RX ReassocResp from f54c002a (capab=0x411 status=0 aid=2)
[ 7821.292152] wlan0: associated
[ 8003.160083] ACPI: EC: missing confirmations, switch off interrupt mode.
[ 8003.662044] ACPI Exception (evregion-0419): AE_TIME, Returned by Handler for [EmbeddedControl] [20080926]
[ 8003.662078] ACPI Error (psparse-0524): Method parse/execution failed [\_SB_.PCI0.SBRG.EC0_.EBTS] (Node f6c140d8), AE_TIME
[ 8003.662210] ACPI Error (psparse-0524): Method parse/execution failed [\_SB_.PCI0.SBRG.EC0_.UBCS] (Node f6c17f00), AE_TIME
[ 8003.662326] ACPI Error (psparse-0524): Method parse/execution failed [\_SB_.PCI0.CBST] (Node f6c18090), AE_TIME
[ 8003.662439] ACPI Error (psparse-0524): Method parse/execution failed [\_SB_.PCI0.BAT0._BST] (Node f6c17fc0), AE_TIME
[ 8003.662558] ACPI Exception (battery-0359): AE_TIME, Evaluating _BST [20080926]
[10068.124071] wlan0: beacon loss from AP f64706b8 - sending probe request
[10070.124073] wlan0: no probe response from AP f64706b8 - disassociating
[10071.219887] wlan0: authenticate with AP f64706b8
[10071.229958] wlan0: authenticate with AP f64706b8
[10071.232927] wlan0: authenticated
[10071.232936] wlan0: associate with AP f64706b8
[10071.239504] wlan0: RX ReassocResp from f551202a (capab=0x411 status=0 aid=2)
[10071.239516] wlan0: associated
[11357.640074] wlan0: beacon loss from AP f64706b8 - sending probe request
[11359.640075] wlan0: no probe response from AP f64706b8 - disassociating
[11360.738427] wlan0: authenticate with AP f64706b8
[11360.740564] wlan0: authenticated
[11360.740575] wlan0: associate with AP f64706b8