Leopard 10.5.7: MacBook WiFi connects, then drops

My old MacBook's built-in Wi-Fi was rock-solid until recently, but just lately it had problems. Disabling RealPlayer Downloader Agent seemed to fix this....

The old late-Tiger, early-Leopard problem of not reconnecting after sleep was fixed in an Apple software update around six months ago.

But just now, after booting from cold, the Wi-Fi kept briefly connecting to my access point (a Cisco 877W ADSL router), then dropping off again - and showing all my neighbours (non-clashing) access points but not mine.

Looking at /var/log/system.log I noticed that each time the Airport en1 interface came up, RealPlayer Downloader Agent started doing things:-

Jul  7 20:17:37 guest43 RealPlayer Downloader Agent[161]: System Configuration Callback!
Jul  7 20:17:37 guest43 RealPlayer Downloader Agent[161]: changed keys (\n    "State:/Network/Interface/en1/IPv4"\n)
Jul  7 20:17:37 guest43 RealPlayer Downloader Agent[161]: changed dict {\n}

So I killed the RealPlayer processes:-

bash-3.2# ps -ax | grep Real
161 ??         0:01.86 /Users/martinjohnson/Library/Application Support/RealNetworks/RealPlayer Downloader Agent.app/Contents/MacOS/RealPlayer Downloader Agent -psn_0_77843
219 ??         0:00.62 /Users/martinjohnson/Library/Application Support/RealNetworks/RPDLAgentHelperD all
249 ttys000    0:00.00 grep Real
bash-3.2# kill -9 219 161
bash-3.2# ps -ax | grep Real
251 ttys000    0:00.00 grep Real
bash-3.2# 

And now the Wi-Fi link comes up and stays up. Maybe it's just coincidence, but to try to make this change permanent, I've been into System Preferences / Accounts / Login Items and removed Real Player. It was always annoying anyway! To be fair to Real Networks, it should not be possible for an application issue to make the Wi-Fi drop out: this has the feel of a race condition in the kernel - maybe caused by the Real application firing off a pointless burst of traffic each time the link comes up - but what do I know.