“unexpected $end” in plugins after moving to PHP5 & 2.1.3

I migrated servers to a PHP5 system and upgraded from WP 2.1.2 to 2.1.3 at the same time, so I’m not entirely sure which is the culprit here…

I have several plugins that no longer work – activating them causes my site to go down (blank page). Checking the logs, in many cases I see parse errors indicating an unexpected $end – like this:

PHP Parse error: syntax error, unexpected $end in /home/scott/public_html/wp-content/plugins/ajax-comments/ajax-comments.php on line 229

In at least one case (OnlineNetworking), a plugin that was working fine on PHP4 and WP 2.1.2 ‘broke’ and the error message indicated there were a couple of extra “}” found – removing those brought the site back, but the admin page for the plugin is kind of messed up.

Are these problems more likely PHP5 related, WP 2.1.3 related, or a combination?

Is there anything I can do to get these to work? (assume I want/need to stick with PHP5).

Thanks,
Scott