As suggested several times before: Try to log in with version 0.5.8. Give it a few minutes, then try again with 0.5.9.
I had the same problem (can't log in with old e-mailaccount). When I install 0.5.8 x64 on Win 7 (as suggested above) I can't log in as the client don't find the servers, "Zeroping Host (RP) = Failed" and "Ezpcusa (Non-RP) = Failed". When I try 0.5.9 x64 it say "Laanx server (Main)", but I can't log in.
So I tried to:
1. Install 0.5.8 x64
2. Open C:\Program Files (x86)\PlaneShift\data\servers.xml and changed 62.173.168.9 in two places to planeshift.subhosting.net
3. Started 0.5.8 x64, now "Zeroping Host (RP)" is responding, and I can log in =
4. I join with one of my characters and play for a minuter or two, then I quit the game
5. I start the game again "as administrator" and choose Yes when it asks if I want to update now, wait for it to update...
6. After a while I get 0.5.9 and it starts up, but I can't log in

7. I quit 0.5.9 and install 0.5.8 x64 on top of the one I just tried, after that I changed servers.xml as above.
8. I start 0.5.8 x64 (without updating) and log in, it works again.
9. I ask for help, and a GM tells me to:
a) Log out with 0.5.8 x64
b) Start Planeshit, DELETE THE PASSWORD and then manually rewrite it again to login.
c) To change my username e-mail I need to talk with Weltall, best in IRC in #planeshift-gmtalk channel or do a petition from my account.
10. I quit 0.5.8 x64, start 0.5.8 x64 again (without updating), delete my password, manually enter it again and join.
11. I quit 0.5.8 x64, I start the game again "as administrator" and choose Yes when it asks if I want to update now, wait for it to update...
12. I start 0.5.9, delete my password, manually enter it again and now I get in

Maybe this can help someone. Next I will try to change my login username e-mail...
PS. You can get 0.5.8 from here:
http://www.hydlaaplaza.com/smf/index.php?topic=40860.0