I'm running GNS3 0.8.2 on windows7 64 bit.
Ping from microsoft loopback interface to router interface through ethernet switch not working fine:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 10.0.0.1: bytes=32 time=22ms TTL=255
Request timed out.
Request timed out.
Reply from 10.0.0.1: bytes=32 time=22ms TTL=255
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 10.0.0.1: bytes=32 time=25ms TTL=255
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 10.0.0.1: bytes=32 time=30ms TTL=255
Request timed out.
Reply from 10.0.0.1: bytes=32 time=21ms TTL=255

Everything works fine if I remove the Ethernet switch. ( Connecting the loopback directly to the router interface).

Any suggestion or assistance is much appreciated.

Verfied on win 7 64 bit, GNS3 0.8.3 version, no problems at all. with or without switch between cloud and router. Pings 100%
Check you lo0 interface cofiguration etc.

uninstalled gns3 0.8.2 and installed 0.8.3 but it didn't help.
I really can't find what I am missing. especially when there is not much things to do either with
the cloud or loopback interface config. Is something required during gns3 installation in order for the ethernet switch to work properly.

Thanks

Try to uninstall all things linked with GNS, it must be done manually. Sometimes old dynamips settings are stored and you got problems.
From control panel remove all progs Linked with GNS, PCAP, Pyton etc.
Delete directory GNS from Program files, Program data.
remove gns3.ini form C:\Users\NAME\AppData\Roaming

It helped me.
And install clear installation of GNS3 0.8.3.
create MS loopack.

reboot (in older versions it was necessary, otherwise ethernet interface do not appears under cloud.)

Regarding MS loopback.
Im using it bridged with my PC NIC as internet cloud.
Check firewall connections, ping allowance.
Everything must work.

I reinstalled GNS3 0.8.3 on a freshly installed win7 32 bit and was surprised to have the same problem. The common point between the 2 machines was kaspersky Pure sec. So I uninstalled Kaspersky and everything was working fine.
It's really strange, because I did closed Kaspersky before and it didn't help.

Thanks for your help.

I am having the same issue and tried several of the fixes proposed but none of them worked.
When I connect the router directly to the cloud it works without any ping drops then not even a few minutes later I get a bluescreen!
Windows 7 x64 loopback working OK, the problem is only with Win 8 Pro x64
I am running the latest full release of GNS3 0.8.3.1; I might try 0.8.4 RC2 to see if that fixes the issue...

Almost same issue i have described here with 0.8.4 RC2

post19019.html#p19019
post19020.html#p19020

Windows 8 X64