i have changed around 30+ times repos in the last 4 years and haven't had problems doing it
be sure that the repo you selected is being updated, some repos are abandoned/outdated
2009 repos are now in general frozen because pclinux 2010 will replace them, this will require a new pclinux installation with a new pclinux that we are still waiting so no date yet
don't forget to press reload each time you change repos and try not to use testing sections unless you know what you want form that section
