As of the last two weeks I have been having potentially two separate issues.

The first one was random system freezes throughout the day. This one seems to have been resolved by disabling power saving features in UEFI.

The second problem is that my system no longer consistently boots to the default graphical target.

I have a workaround: if I edit my kernel command line in grub to say "systemd.unit=multi-user.target" I can boot without issue and after that I have had good success with logging in and running: sudo systemctl isolate graphical.target

Reproducible: Sometimes

Steps to Reproduce:
1. Boot my computer
2. Sometimes it works, sometimes it doesn't
3.
Actual Results:
The boot process stalls. When I eventually get into my system I can see this logged as the last line from a failed boot:

Mar 24 09:22:45 systemd[1]: user: start operation timed out. Terminating.

On a successful boot I can see this:
sudo journalctl -b -1 -u user
Mar 24 09:21:59 systemd[1]: Starting user - User Manager for UID 60578...
Mar 24 09:22:00 (systemd)[2675]: pam_unix(systemd-user:session): session opened for user gdm-greeter(uid=60578) by gdm-greeter(uid=0)
Mar 24 09:22:45 systemd[1]: user: start operation timed out. Terminating.

Which made me think this is a GDM issue.

Expected Results:
System boots normally.

Additional Information:
Another user has reported, what seems to me, the same problem on the forums: https://discussion.fedoraproject.org/t/fedora-freezes-just-before-login-screen/183173/9