mount problem

[CallipyG]

Whenever I try to install RH 5.1, a message always pops up...

mount failed: Invalid parameters

it always pops up right after I choose the packages to install, right before the 
installation begins.  I partitioned the drive successfully, and because I don't even 
have any clue what's causing an error like this, I don't know where to begin.  Thanks.

~CallipyG