I downloaded the ones you linked in the mentioned post http://forum.avast.com/index.php?topic=120531.0 . I have a 32 bit win7 system so i downloaded Rufus, the win7 32 bit rc.iso and FRST.

IN Rufus i used the following settings:
Device: (I:)
Partition: MBR partition scheme for BIOS or UEFI computers
File system: NTFS
CLuster size: 4096
I checked Quick format, creat bootable disk using: (selected the downloaded ISO), and Create extended label and icon files

I just tried it again and it stopped at the black screen with the white mouse cursor again.