are you trying to create or alter partition sizes during install ? this causes crashes for me on occasion. i found i create the partitions first, then run the live dvd's to install. use the windows partitioning tools, or the kde partition manager which is on some live dvd's, gparted or something like that.
edit* basically you want to create the primary and or extended partitions first, then run the install to those partitions you created else where. LVM's will still work, just create a primary partition first to install to.
if you have more trouble or questions post some extra details on your layout.
multi-booting Sabayon 5.5 kde 64 bit and others
intel e6600 @ 3.0 ghz core duo
6gb ddr2 800
biostar tpower i45 motherboard
nvidia 9800 gt
3) 7200 sata's non-raid