Hidden SSID is really not a security measure at all. The most noticeable effect of hiding the SSID is to make it less convenient for legitimate users to find the network and connect to it. Any hacker can easily see the network even when it doesn't broadcast the SSID. If you want to secure your network, you should use WPA or better yet, WPA2. WEP is no longer considered at all secure.
I have not had the SSID or the network "go missing" using WBR-2310 version 1.05 firmware, but I have had the router fail to allocate an IP address to wireless computers via DHCP. It says the DHCP request was successful in the log, but the computer doesn't get it. After I reboot the router, the computers get connected. A few days later, we're back to square one though, and I have to reboot in order for wireless computers to connect. There is never any problem with the wired computers getting IP addresses via DHCP.