After couple of trials it looks like I understand what is problem and when this problem occurs.
The following is my analysis
This problem mainly occurs when the PIC is sending data towards the RS232 to log it to the Terminal on the PC. When the PIC is power down and the Screamer comes up to download it tries to open the port but it will be in waiting state as the PIC had intialized and kept it ready for next transmission, thats when the VB code is receiving an error code of 8020. For this the error message that has been put-out is not at all matching with what is happening actually.
If the PIC initializes but send no data at all then this issue never comes up. Everything runs smooth
The work around to this issue, is un-plug the cable and put-it back and then try downloading the HEX file, which will result in a successful download.
In my laptop, I have converter from USB to serial. My guess is that this happens when converters are around. Not sure whether a serial port on the mother board is used, whether this issue comes up or not.
Anyway, now then I figured out and I have a work-around for this issue, please suggest me is there any other option I could have. Updating the converter's driver would be one of them.
Also I like to thank Sparkfun for this tool because this is only bootloader that works on my PIC 16F877A, the others either fail in writing because they are not aware of the fact that this PIC has a different approach of flash writing or the application they provide will not be able to detect the bootloader that is there in the PIC or they do not have one, I need to modify which is similar and give a try.
Let me know if there are any further comments or suggestions on the above