I am using the gns3 for a long time and initially I found this behavior of GNS3 that while working with the router consoles they disappear and after this when I try to reopen but its near come on again since I restart my gns3 program. Sometime when I start the gns3 and open the console it disappear without any error, After a long search on internet and my experience of using gns3 I have come to know that you can get rid of such behavior of GNS3 by following method.
· latest version of GNS3: Always use the latest version of GNS3 which have less bugs and lot more features, you can download the latest version from http://www.gns3.net/download
· Use other than 2600 series IOS: Make sure you are using a fresh and correct copy of IOS which is error and bug free, my experience of using 2600 series IOS is bad mostly they show such behavior and get hang. So try other series of IOS like 3600 and 7200 if you are facing such problem.
· Calculate the idle PC values for routers i.e. Right click on router and then click on idle pc
· Also verify the putty path from Edit\Preferences\ General tab\"Terminal Command"
"C:\Program Files\PuTTY\putty.exe -telnet %h %p"
"C:\Program Files\PuTTY\putty.exe -telnet %h %p"
Please leave a comment if it is informative for you and also add your experience of troubleshooting this problem.
Thanks for Reading.