For a quite some time now I’ve been happily using Ubuntu on my desktop and the emacs-snapshot-gtk package of GNU Emacs to get good fonts and a recent Emacs. I edit a lot of Perl code and use cperl-mode to do so (as I have for years). However, recently I’ve noticed the color syntax highlighting to be rather buggy. At seemingly random times it’s loses the colors for a fairly large chunk of code. Other times it just messes up a few lines.
I try to flip font-lock-mode off and back on but the problem persists. It’s become annoying enough that it’s a real distraction. At times the colors flip on and off with every other keystroke, as if the matching engine has become a state machine which every other state disables highlighting. It’s rather odd considering how I’ve used GNU Emacs and cperl-mode flawlessly for many years now.
All the while, indentation and paren/brace/bracket matching seem to work just fine.
Anyone seen this? I’ve done some searching but haven’t turned up anything concrete. It seems to have become an issue when I started upgrading my computers from Ubuntu 9.04 to 9.10. Does this ring a bell for anyone else?
Jeremy Zawodny's blog 
I’ve never been able to get cperl-mode to color anything. I always have to use just plain old perl-mode.
I had a number of annoying issues with emacs-gtk on ubuntu 9.10 as well as 10.04 (mine were with java mode, however). I ended up just compiling gnu emacs from source and left it at that. I too just use regular perl-mode so no insight on cperl-mode.
Interestingly, I’ve found that emacs23 from Maverick’s repository yields better results with cperl-mode’s syntax highlighting than emacs-snapshot. Checking cperl-version for both versions shows that one uses 5.x, and the other uses 6.x. I guess 6.x has crappy syntax highlighting.