I'm not running the Gnome version of PCLOS, so I can't help you firsthand -- but I suspect that the reason you're having trouble updating is because the repositories are currently in a state of flux. (If this info is incorrect, I hope a Gnome user will chime in and confirm that they are not having any problems with updates).
Texstar and the other developers are preparing a new 2010 .iso, which is almost ready. So we haven't had any updates for the past few weeks ... If we can be patient, we'll be rewarded for the wait. The standard answer around these parts as to when the .iso will be ready is: "It'll be ready when it's ready
For more info, please take a look at this thread. (There are other threads as well, but I didn't look for them all):http://www.pclinuxos.com/forum/index.php/topic,68287.0.html
"Synaptic not updating??
" 10 Feb. 2010.
If you're interested, you can follow the development(s) via Twitter. (You don't have to set up a Twitter account in order to read the messages):http://twitter.com/iluvpclinuxos
I hope this helps answer your question. You seem to be fairly new to this user forum, so I didn't want you to feel like you were being ignored. So "Welcome aboard!"