"Unloading user registry hives might take a while..."

[antdude]

Once in a while, SpyBot S&D v1.6.2.46 will freeze with "Unloading user registry hives might take a while..." message after scanning (nothing found) and exiting the program in my old, Windows XP Pro. SP3 machine. It's very rare though, but why does it happen?

http://i.imgur.com/inKqR.gif for the screen shot when it got stuck when exiting.

Process Explorer v15.05 on this spybot process: http://pastie.org/private/qtt0mp2u4tbx011fcb7bq

Thank you in advance.