If he tried to install FMCB to the Memor32-MC (where memento is "flashed" on), I think it is because of the bad FAT, (which) the Memento-Flash produces.
A format with the installer, or ffgrievers MCA should be the solution then.
PS2 V7/DMS3 V2 (FW:2.4b7); Seagate Baracuda 200GB
PS2 V7/CC1.0 (FW:34 hacked v2 BM:2.1.6); Maxtor DiamondMAX9 PLUS 160GB
PS2 SCPH-30004R; NoMod+NoLaser
3xSony MC 8MB
MAX/Datel 16MB with Boot-CD
Custom FMCB 1.8b+ Beta-Build, my AIO 0.5, Sony&xRhino-Linux