Serial Communication (RTS) and Windows 7

I am developing Delphi application on Delphi 2010 XE RAD Studio under Windows 7. My application talks on the serial port non-stop. I am using AsyncPro for Delphi 2010. Serial communication and everything else on the computer I develop with works great without any problem. However, when my release version of my application is run on another Windows 7 system, serial communication completely fails. We probed the serial communication itself for an answer and found out that Request to Send (RTS) line is not dropped right after sending all the bytes, whereas on my development computer RTS line is dropped correctly.

Even when I explicitly drop the RTS line to low or false state, RTS line doesn't drop right away but after good 15 milliseconds. Thus, serial communication on my release version is failing.

Am I missing important information about Windows 7 and serial communication issues?

UPDATE: I just found the bug with my Aysncpro 5.0 for Delphi XE. It is weird. When my Delphi XE IDE is open or running, my program is communicating flawlessly. When I shutdown or close my Delphi XE IDE while my program is running, the same program doesn't communicate very well or it times out.

Chime in if you have any idea why it is happening.

Any help will be appreciated.

Thank you,