Problem at startup - lockup loading swap

[Micha]

I'm trying to help a friend over the phone, so I don't have all the details,
but I would be happy for some pointers if anyone has them

The machine with mostly up to date debian unstable on occasion decides to lock
up for several minutes after or at the point of mounting the swap partition.

Previous time that happened starting a different kernel solved the problem.
This time all kernels showed the same issue, we though that it was in a hard
lockup, but after several minutes it freed up and continued booting.

We tried running swapoff -a, mkswap and swapon -a. On the call to swapon the
machine complained about not finding the swap's UUID (which didn't match the
value reported by mkswap). The only information in /etc/fstab regarding UUID is
commented out.

Any ideas about what the problem is and/or how to disable UUIDs altogether as
they seem to be giving constant trouble?

thanks