I just had an interesting experience while installing Fedora 16 on my primary workstation. It took me about 3 days and many attempted installations to figure this out. This is not a review, just a bit about my experience.
At first I wiped out my hard drive entirely since it has been several years since I did a really clean installation. That is, a complete wipe out of my hard drives—after first making certain that I had multiple good backups. Over time much cruft can accumulate from old application configuration and data and I wanted to get rid of everything except data I really wanted to keep.
The initial installation of Fedora 16 appeared to go well using the default choice of EXT4 for the filesystem type. After starting to make configuration changes and restoring a few directories in my non-root user home directory, KDE started crashing on a regular basis. It would indicate problems with Segment Faults. This is not good and can mean many bad things.
After installing several times with similar results, I decided to go back to Fedora 15. During the installation, I used EXT3. I had previously experienced an occasional problem with Fedora 15 while using EXT4, but nothing particularly repeatable. Many of the problems were during installation using EXT4 and I would get errors indicating that a specific package was not able to be installed. Looking at the log terminal (Ctrl-Alt-F3) most errors appeared to be on the DVD, but the DVD always tested as having no defects at the beginning of the installation.
My decision to use EXT3 was kind of on a whim, but the next install went without problems and I had no problems doing basic configuration. So I decided to reinstall Fedora 16 using EXT3 instead of EXT4 and have had no problems since. This is using the same physical hardware and the exact same partitions and logical volumes.
I think this indicates, at least to me, that there are still some bugs in EXT4. I have not however, seen this problem on some of my other systems. Perhaps it is the larger 1.5TB drives I am using on this system.
I hope this helps by preventing you from spending 3 days to discover and resolve this problem.