Thanks esmi, that solved my problem! Before I deleted the folder I deleted all cookies associated with my site, just to see what would happen. It also “solved” the problem, at least temporarily until I logged into the admin area, which rendered the blank pages phenomenom again.
Current WP version is 2.7.1. According to the plugin info it requires 2.7 or higher, so I thought it would be safe…
Anyway, thanks again for your support!
thomas