The way Dynamips/GNS3 works is by directing the console to a TCP Port. This is a snippet from my machine with one router in GNS3, which shows the Dynamips Process has created the console port using port 2001.
Code:
Proto Local Address Foreign Address State
TCP 127.0.0.1:2001 0.0.0.0:0 LISTENING
[dynamips-0.2.8-RC4-community.exe]
If when you run the netstat command you see a program other than Dynamips listed under your base console port, then that is what is stopping Dynamips from working correctly. You could then change the console base port to another value in GNS3 preferences.
If the process is shown as Dynamips it is possible that another instance of Dynamips hasn't shut down correctly. So try closing GNS3 and making sure that no Dynamips processes are shown in Task Manager.