I'm using the last putty version and can't create two different sessions (Needed when I need to do SSH TUNNELING and log the server for maintanance)
Here is the log from the second connection that got failed:
Looking up host "[IP]"
Connecting to [IP] port 22
We claim version: SSH-2.0-PuTTY_Snapshot_2011_04_14:r9149
Server version: SSH-2.0-OpenSSH_5.8p1-hpn13v11
Using SSH protocol version 2
Server supports delayed compression; will try this later
Doing Diffie-Hellman group exchange
Doing Diffie-Hellman key exchange with hash SHA-256
Then it hangs. It happens only with putty. I can log on with OpenSSH client (through linux) with any number of sessions that I want.