I've been experiencing odd network problems with my MacBook since upgrading to OS X 10.4.10 - sometimes the Mac won't see my wireless network, other times it drops off it, inexplicably.
I know it's not my Base Station, because other users here don't suffer the problem - the old 12-inch PowerBooks and other Macs we host here are all as stable as ever.
At first I began to panic, believing the Mac's AirPort Extreme card needed replacing, but it seems this is not the case.
It appears some systems have experienced unusual network performance since making the upgrade.
I found the best account of these (oddly enough) on a Mac/Windows-focused website.
The site explains very similar problems to those I have been experiencing, suggesting that an occasional restart appears to solve the problem.
I have found that restarting the Mac seems the only immediately available solution to the problem, but some users say they have simply reinstalled their OS back to OS X 10.4.9.