I had the same problem installing FC6 to a 160GB hard drive.
I solved the problem by specifying the hard drive geometry when doing a reinstallation, i.e. when the installation DVD boots enter the command
linux i686 /dev/hdc=19457,255,63
to begin the installation.
I got the hard drive info by using the installation DVD to boot into rescue mode, then running the command
# fdisk -l hdc
Disk /dev/hdc: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/tracks, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hdc1 * 1 7649 61440561 7 HPFS/NTFS
/dev/hdc2 7650 19304 93618787+ 83 Linux
/dev/hdc3 19305 19457 1228972+ 82 Linux swap / Solaris
Note, FC4 previously installed no problem (without the additional linux arguments) to the same HD.