some fixes went into scanning with build 48. Can you please retest with newer 
version. Also, ty and scan before associating, then also while associated to 
see any discrepencies.

Could not obtain any more information on this, and no new reports of it on the 
mailing list. Marking as worksforme.

Issue still occurs. 
 
Hardware: HP compaq nx7000 
Wireless Card: Intel Corp. PRO/Wireless LAN 2100 3B Mini PCI Adapter (rev 04) 
OS: SuSE Linux 9.1 Pro, kernel 2.6.9 vanilla 
IPW2100 version: 1.0.2 
Firmware version: 1.3 
 
I am associated with an access point (Apple Airport Extreme), and sometimes the 
usual `iwlist wlan0 scan` will return the proper result: 
 
# /usr/sbin/iwlist wlan0 scan 
wlan0     Scan completed : 
          Cell 01 - Address: 00:0A:95:8C:D3:3A 
                    ESSID:"OpenAP" 
                    Protocol:IEEE 802.11bg 
                    Mode:Master 
                    Channel:10 
                    Encryption key:on 
                    Bit Rate:54Mb/s 
                    Extra: Rates (Mb/s): 1 2 5.5 6 9 11 12 18 24 36 48 54 
                    Extra: Signal: -47  dBm 
                    Extra: Last beacon: 74ms ago 
 
while seconds later, it returns nothing: 
 
# /usr/sbin/iwlist wlan0 scan 
wlan0     No scan results 
 
This seems to happen randomly, however I have not tried to systematically 
analyze the behaviour so as to be certain. 

Dimitris, are you running as root or as a regular user when you run iwlist? 
Also, what does /sys/bus/pci/drivers/ipw2100/*/scan_age report?

Liberty:/home/reverant # iwlist wlan0 scan 
wlan0     No scan results 
Liberty:/home/reverant # whoami 
root 
Liberty:/home/reverant # 
cat /sys/bus/pci/drivers/ipw2100/0000\:02\:02.0/scan_age 
15000 

I've put in a fix in 1.0.5 that might fix this (if we're lucky)

+OK, will test and report as soon as 1.0.5 becomes available. Thanks! 

Note from Dimitris on version 1.0.5:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Hello, I haved been testing it for the last couple of days, with mixed 
results. I have two access points. An Aple Airport Extreme Base Station, and 
a generic Netgear .11g. Most of the time, both are properly detected. 
However, some times, only one (Netgear) is detected properly. Example:

Liberty:/home/reverant # iwlist eth1 scan
eth1      Scan completed :
          Cell 01 - Address: 00:0A:95:F7:1B:54
                    ESSID:"Cataclysm"
                    Protocol:IEEE 802.11bg
                    Mode:Master
                    Channel:10
                    Encryption key:on
                    Bit Rate:54Mb/s
                    Extra: Rates (Mb/s): 1 2 5.5 6 9 11 12 18 24 36 48 54
                    Quality:0/100  Signal level:-46 dBm  Noise level:-256 dBm
                    Extra: Last beacon: 16ms ago
          Cell 02 - Address: 00:09:5B:A3:EA:24
                    ESSID:"NETGEAR"
                    Protocol:IEEE 802.11bg
                    Mode:Master
                    Channel:11
                    Encryption key:off
                    Bit Rate:54Mb/s
                    Extra: Rates (Mb/s): 1 2 5.5 6 9 11 12 18 24 36 48 54
                    Quality:0/100  Signal level:-56 dBm  Noise level:-256 dBm
                    Extra: Last beacon: 13ms ago

Liberty:/home/reverant # iwlist eth1 scan
eth1      Scan completed :
          Cell 01 - Address: 00:09:5B:A3:EA:24
                    ESSID:"NETGEAR"
                    Protocol:IEEE 802.11bg
                    Mode:Master
                    Channel:11
                    Encryption key:off
                    Bit Rate:54Mb/s
                    Extra: Rates (Mb/s): 1 2 5.5 6 9 11 12 18 24 36 48 54
                    Quality:0/100  Signal level:-58 dBm  Noise level:-256 dBm
                    Extra: Last beacon: 12ms ago

The 2 scans took place with a 3 second interval. I did not notice been 
deassociated from the Apple base station ("Cataclysm") at that point. 
Overall, definate improvement over the previous version I had (1.0.2), but it 
seems it still needs some work. Let me know what I can do more to help you 
track it down.

Dimitris

Silimiar case happens in our Compaq X1000, with LinkSys WRT54G AP. 

AP is configured in mixed mode (b/g), without WEP.

Sometimes the AP can't be detected in Compaq X1000 for a long time. 
While other machine can detect the AP easily at the same time.

The difference from this bug is that if we can't detect the AP, we can't 
assoicate with it too. While other machine (like SONY VAIO) can associate with 
the AP easily. 

% cat /sys/bus/pci/drivers/ipw2100/0000\:02\:02.0/scan_age 
15000 

When we reload the driver, we can associate and detect the AP. 

Issue only occurs sometimes. 

logics_sbux	if crystal can reproduce this, it could be useful to see the 
output of the debug log during an iwlist scan when the AP is not detected with 
debug_level set to 0x43fff
logics_sbux	and assign to Yi

Setting to needsmoredata. When above info is provided, please assign to 
yi.zhu@intel.com (Zhu Yi)

Requesting more data or close, since this has been sitting for over half a
year.

I tried on 1.0.8, this bug has not occured. Since nobody reports this problem 
on the latest version, I verify this bug. If anyone find this problem happen 
again, please reopen it.

Sorry, if i'm too late. I had the same problem and googling showed that very
much people have this problem. My solution was:
I noticed that my single ap chose a working channel itself and it was one of
1-13 (and mostly it was either 6 or 13). But when i did
igorg@falcon:~$ sudo /sbin/iwlist wlan0 channel
wlan0     19 channels in total; available frequencies :
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Channel 36 : 5.18 GHz
          Channel 40 : 5.2 GHz
          Channel 44 : 5.22 GHz
          Channel 48 : 5.24 GHz
          Channel 52 : 5.26 GHz
          Channel 56 : 5.28 GHz
          Channel 60 : 5.3 GHz
          Channel 64 : 5.32 GHz
          Current Frequency:2.412 GHz (Channel 1)
i noticed there was no channel 13 -- so when ap operates on channel 13 it
cannot be seen by iwl3945. I made the ap to always operate on channel 1 and
there is no problem for
igorg@falcon:~$ sudo /sbin/iwlist wlan0 scanning
wlan0     Scan completed :
          Cell 01 - Address: 00:1B:11:73:12:36
                    ESSID:"ignetwork"
                    Mode:Master
                    Channel:1
                    Frequency:2.412 GHz (Channel 1)
                    Quality=59/100  Signal level=-72 dBm  Noise level=-127 dBm
                    Encryption key:on
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s
                              12 Mb/s; 24 Mb/s; 36 Mb/s; 9 Mb/s; 18 Mb/s
                              48 Mb/s; 54 Mb/s
                    Extra:tsf=00000000433e1181
to always find the ap. I think when there are many aps around they dinamically
select different channels, so accidentally may choose a channel that cannot be
caught by iwl3945.