The swap disk should be no bigger than 4 GBs for your system and I would
actually go for 2 GBs to equal your RAM as swap space is way over rated,
IMO. So you had way too much swap to begin with (and probably still have)
which is likely your problem. Since you would have to physically (and
consciously) remove the old swap partition and if you have not done so, then
it probably still exists and you may be compounding your problems. Ubuntu
will use whatever swap space is designated as such and this includes more
than one swap space.

Wiping out the hard disk will NOT resolve your problem. You need to delete
partitions that are set aside for swap or reformat them at the very least
(the easiest solution) using the Partition Manager in Ubuntu. Once done
reboot and you should find a leaner and better system.