I've been workin on getting my usb device to communicate through a virtual comport and found out the following :
0) I use PIC18F2455 and Microchip CDC example code.
1) My system is Windows Xp Sp2,and my device is working correct.
2) I check the USBSER.SYS version is 5.1.2600.2180 (XP's version).
3) When I use my device in Windows 2000 Sp4,it didn't work correct.
when I send command to my device,and the response of my usb device is incorrect. 4) It doesn't work with USBSER.SYS version 5.0.2195.6655 (2000 version).
I found this problem of usbser.sys(win2000 version) everywhere.