Problem with UART read - VF50

We have started developing our WinCE6 application on VF50 and we have encountered a problem with UART driver.

We are using VF50 for real time application like patient monitoring system.

We are using internal UART of VF50 for reading data from a other device (Its an ECG module in our case).

We are using UARTB and the UART is configured for 460KBPS baud rate.

The problem we see is communication with this port(UARTB) does not work correctly. Writing to port works fine but receiving data does not. Sometimes data from the port will not be received for over 500 to 700ms.

API which we are using to read the com port is : ReadFile()

UART Driver used is vybrid_serail.dll

This is also being handled on otrs.