Unable To Connect To MySQL Database?

I have written a new app in VB.net as a front end to a mySQL database held on a PC on the LAN running Windows XP. This worked fine for a while. The PC running the mySQL server started locking up (XP errors, not mySQL errors according to the event logs), so I decided to have a go installing Ubuntu to run the mySQL server to see if that was more stable.Ubuntu 11.10 is now installed, and mysql server is also running. I have imported the old sql database files and the mySQL workbench shows all tables are imported successfully.

HOWEVER, I cannot get my VB application to connect to the database now it resides on Ubuntu - just returns "Unable to connect to any of the specified MySQL hosts" when i try to open a connection. I am fairly new to Ubuntu and MySQL, and don't know if the fault lies with the O/S (a firewall config problem perhaps?) or if I need to do something different with mySQL.I can ping the Ubuntu pc from the client pc and vice versa.I have used ufw to open port 3306 on the server The ufw logs do not show any errors when I try to connect from the client pc, so I don't think it's a firewall problem (but could be wrong). I thought it may be something to do with the usernames I use in the connection string, but when I change these (deliberately use the wrong password for example) I get the same message, rather than a username/password error Is anyone else using a client PC running Windows (W7 or XP) to connect to a mySQL database running on a Ubuntu server?