Wireless Troubleshooting

I recently got my wireless router back from D-Link. (It had been sent in for repairs to fix its habit of power-cycling every 30 seconds or so.)  Since it came back, I've been happy with the results I've been getting (no mysterious power-cycling or sudden losses of connectivity), with one minor exception.  Since I got it back, I've had issues connecting to idun (this machine) immediately after I reboot loki (my Windows machine).

Following a reboot, I am unable to connect to the webserver on idun from loki (although I can telnet into it and get the HTTP 400 error page), nor am I able to SFTP (although I can SSH), nor export an X-Windows program that is any more complicated than xterm.  What's more, it's only idun that these difficulties arise with.  I have no problems connecting with any protocol to sovereign (DNS server and router) or the XBox.  The problem immediately rectifies itself if I reboot the wireless router (which is acting as a switch, since its WAN port is unplugged and unconfigured), unless, of course, I reboot loki again.

I've been to D-Link's site, and their FAQ and knowledge base is a little less than helpful (consisting largely of things like "How do I disable SSID broadcast", you know, the sort of general technical support questions that 2 minutes with the manual or a cursory glance at the router's config interface would reveal).  So basically, has anyone else had these problems, and how did they fix them?