Yeh, if the files can't be written to, they're of little use; you should go and chmod all the files that fail 666, and all of the directories that fail 777.
If it still won't work, it could be a problem with the "math" used to define pagination; theres a bug in PT's as well on this which fails for the post which starts a new page (at least there was prior to 7.3, I haven't had the chance to test it in 7.3 yet)
