Hi Javed,
I can able to execute single TC and getting proper result.
The issue was not resolved quite long time and I did the below,
1. Checked firewall for Devtest - its proper
2. reset my system profile - dint work
3. Created my profile in another computer - it works
4. Finally, re-build my machine - it works
So can't identify exact issue and not sure any other software corrupts devtest. Now after re-build all works as usual.