You’re actually the first person I’ve heard of using it with the wp.com toolbar.
Since that overwrites the whole toolbar, and isn’t hookable, you’re unable to use most features (like purging a specific page). The plugin auto-purges most things for you, though, so manual purges should be rare.
To make sure I understand the situation and can help you resolve it properly, can you please answer the following:
1) How long have you been using this plugin?
2) How long have you been using the WP.com toolbar?
3) Why do you need to manually purge the cache?