In order to detect whether you are infected by HackDefender, please download this utility: http://bagpuss.swan....torv0.62.zip
If you are infected you can try the following: If your system drive (usually C is formatted with the FAT32 file system, simply create a bootable floppy, boot from it, and delete the directory from the command prompt.
If your system drive is formatted with the NTFS file system, download Bart's PE builder from http://www.nu2.nu/pebuilder/ in order to create a pre installed environment cd image. Burn that image and boot using the CD, use then the utilities inside the PE in order to delete this folder.
You can read more on HackDefender here: http://bagpuss.swan....comms/hxdef.htm