I have no idea if it'll fix everyone's problems but it fixed my port forwarding/virtual server issues.
Here's what I did:
1. Press reset button until the lights turn off and on 3 times
2. Restore factory defaults
3. Re-flash 1.31 firmware
4. Restore factory defaults
5. Repeat #4
6. Configure everything manually, rebooting whenever it asks.
This was all done using Internet Explorer 6 I think that's a key point here, since I originally tried with IE8 and Firefox without success.
Everything seems to be working fine, I have DNS Relay off though even when I had it on I didn't experience any lockups like some people here do. I also manually setup OpenDNS (208.67.222.222 and 208.67.220.220) rather than using that Advanced DNS Service.
My connection is PPPoE based, and the WAN port is set to 100Mbps rather than Auto and I also have Multicast streams enabled. SecureSpot, GuestZone, Wi-Fi Protected Setup, Graphical Authentication, Auto Check Firmware, Dynamic Fragmentation are all disabled.
Not sure if UPnP works though since I don't use it, however it is enabled. Same goes for SharePort.
I think that about covers my general configuration. Again, everything was done in IE6, I haven't changed any settings from any other browser.
Not going to guarantee it'll fix your problems but no harm in trying (assuming you have access to IE6).
EDIT: One more thing, I have the A4 hardware revision.