Avast CD doesn't work with USB CD Drive

I have installed windows XP on my machine and i am trying to boot an Avast with the BART CD on my laptop from the CD drive which has been connected to an USB. But i am just not able to boot it. Can anybody help me to do this task on my XP laptop. I do not have any idea that where i would be going wrong.

There might be something wrong with the copy of BART CD which you are trying to use on your laptop. With the newest release of an AVAST BART CD, the software is compatible with all the Windows file systems that is NTFS, and storage less common, such as SCSI / RAID . In all-purpose BART would be able to work on all disk devices on which Windows can work which also Includes exceptional disk systems , as on some servers , specific manufacturers.

Here i have given you some basic things which you should keep in mind for booting from usb drive.
1. First of all your machine's BIOS should be supportive for booting from a USB flash/pen/key drive.
2. Flash drive should be having boot/system files.
3. The flash drive must have bootsector area.
4. Giving references to drive lines in an autoexec.bat and/or config.sys files might result in an error afterward.

Here is a method to make your flash drive bootable. You have to download the mkbt20.zip from the bootdisk.com and then extract it in temp folder which you have to create. Go to the DOS and then open the directory where you have extracted MKBT and then type command "mkbt -c a: bootsect.bin". Now format your flash drive in FAT or FAT16. Now type mkbt -x bootsect.bin Z: in DOS where "Z" is drive letter which shows flash drive.

I suggest you to try USB Flash Drive Utilities by HP/Compaq which even works with other brands of flash drives also. First you have to install HP USB Disk Storage Format Tool. Then choose for the Device and the File system from the drop down. Now install HP Drive Key Boot Utility for proper drive. Now select for changing the Configuration then select Hard Drive and then Create New Filesystem. Now choose for HP Firmware Flash Package.

If suppose you do not have a floppy drive then i suggest you to use chitchat.at.infoseek.co.jp where they have provided the virtual floppy driver with which you get an A: drive which works as same as real floppy drive. Though it is not user friendly but once you get to know it then it works without any problem. You may use a "raw write" utility like dd for windows to write the floppy image directly to your USB thumb drive.