Can't upgrade to FC6 from FC4

[Jim Lowman]

The install is dying when I try to upgrade from FC4 to
FC6 on my AMD64 3400+ machine.  It freezes just after
identifying the video card, which is a nVidia GeForce
6600.

Everything was running fine with FC4.  I thought the
Audigy Sound Blaster card might be the problem and
pulled it, but no joy.  I have tried to install both
the 32-bit and 64-bit versions of FC6 with the same
result.

Any ideas?

Thanks in advance...Jim