Windows 7 (x64) Arduino UNO serial Xon / Xoff

Hi,
I am using Win7 (64bit) together with Aduino Uno, using Aduino 0022. Installation of USB/serial driver was succesfull. uploading etc. is working fine.
But when I am using the Xon/Xoff protocol on the installed COMx, I am receiving the Xon and Xoff characters in the used application. Because they are transmission control characters I think they should suppressed by USB driver.
Anyone having the same problem and/or solution?

Excuse this question: aren't we advised to use no flow control with Arduino and XBee's ?

Maybe that's true. But I am not aware.
Just try to use an existing arduino uno project. It's specifying to configure xon/xoff on COMx.
Result: mentioned problems with win7 x64. As far as I understand other members of the project have no issues with 32bit systems.