In PSoC Creator 2.0, bootloader host program was enhanced to ensure support for future PSoC devices. This has resulted in the bootloader host program taking slightly more than a second to initiate a transfer, and this causes the bootloader to close the window for download.
To correct this issue:
1) Open the bootloader project's .cydwr file.
2) Go to the System tab and expand Bootloader settings.
3) Change the "Wait For Command Time (10ms)" parameter value from "10" to "200".
4) Rebuild the bootloader project.