Activating WP Super Cache Shows Blank Fatal Error

When I try to activate the latest WP Super Cache on my blog, I get a standard “Plugin could not be activated because it triggered a fatal error.” error, but without any further details.

I’ve tried increasing my WP memory to 64mb (had some memory issues before), uninstalling, deleting, and reinstalling the plugin a couple of times, disabling and removing dead and unused plugins, but the error persists.

I checked my server and PHP logs, and I didn’t find any PHP errors. I have it working fine on another WP 2.9 installation on the very same server (under an addon domain).

What should I do?