Does rebooting the laptop fix the issue too, or only just saving settings on the router?
You could try to do a complete reset to default settings (small button on rear) to clear the problem (after first saving your configuration settings to file).
There are some firmware updates that might apply to your router here, but try any other suggestions that might come along first.
I recently purchased a Level One wireless router model WBR-3408. It is connected via cable to 2 desktops, running on XP Pro and Vista Home Premium. No problems with either since Day 1.
I also connect wireless to a laptop running XP Home. Initially there were no problems, but lately it could not detect the network (SSID broadcasting enabled all the time). After tinkering around, I realised that everytime it cannot detect the network, all I have to do is to open the setup of the router using one of the desktops, login to the wirelsss settings page and just save the settings (without changing a single setting!) and everything will be OK for a day or two. Then I have to repeat the whole process of logging in again to router setup.
I'm quite a newbie to networking, so there could be a simple fix to this problem that I'm not aware of. I have read the manual, but I can't see a solution to this quirk in it. I know this is not life-and-death, but it is irritating.