This annoying delay used to happen every time I dual booted an existing Pclos install with a 'raw' Debian install. The Debian installer reformats the existing swap file, whereas most distros I have used just see it and use it. The reformat changes the UUID of the partition. In my experience there is no message at text boot screen, just a long pause and then boot proceeds. Never did work out what the machine is deciding?
Anyone who dual boots Linux very often ( and uses Legacy Grub in the MBR) will soon learn to love drive partitioning using Labels ( or even old sda) rather than UUID. Pain in the posterior I reckon!!
Note to self:.. Reminds me I don't have enough ram in my test machine for using Virtual Drives properly.