Hi victorist ... no you are not alone. I installed a DIR-615 HWv:C1 FWv:3.11NA in September of 2009 and have had the same problem ever since. The first time I logged on wirelessly with no problems, but if I disconnected and tried to log back in ... "Limited or No Connectivity". The only thing I could figure out was that the wireless DHCP server would not assign a valid IP address. I did notice that if I did not log in for a while (a few days) I could get back on. This most likely is a result of the lease expiring on a specific MAC address. Once this happens, the wireless DHCP server works again. My solution was to manually set an IP address for my, or anyone else's, laptop and this has worked fine. I got back in to the location today to do some maintenance and decided to check and see if there were any firmware updates that might address this issue. I found two FW updates and FWv:3.12NA states "Fixed: Wireless connection issue". BS! I don't know what wireless connection issue they fixed, but it wasn't this one. You seem to be correct in your assessment of the special characters in the WPA password being the problem (special characters include the "space"). I am running the router in b,g,n mode and when I eliminated the spaces in my password, I could repeatedly log in wirelessly just fine. Thank you for your diligence on this topic as I probably would have not figured this out without it.
On another note ... as I mentioned above, there are two FW updates from my original FWv:3.11NA. When I installed FWv:3.13NA, I lost my internet connection. I then downdated to FWv:3.12NA and got my internet connection back. Really D-Link, do you even test the firmware before you release it?