How to figure out what is blocking my connection on Windows 7?

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http://serverfault.com – I have a program that uses a server's port 1099 but my computer cannot connect (times out). The PC having the trouble is running Windows 7. I have disabled Windows Firewall, the antivirus, and the router has all ports open. Still I cannot connect to the server. I am using telnet 1099 but cannot connect. Meanwhile, other PCs, on another network can connect with no problem. Appreciate any tips for troubleshooting. (HowTos)