Testcomplete Error: getting error when try to run multiple scripts at same time

created an project with multiple scripts when try to run the whole suite the first script always runs fine but not the rest with following error.

"Cannot obtain the window with the window class 'IEFrame', window caption '*' and index 0. See Additional Information for details."

looks like it won't open the browser for 2nd script. has anyone enncountered same issue.

if runs the scripts one by one it works fine.