Mollom stops working until I manually clear cache.

For some reason, Mollom stops working on my site until i manually clear cache and then it will start working again. I've been having a look at the site reports and mollom will work for several hours successfully catching spam but then will just disappear and I will get no more reports until I clear cache.

I also have Spambot module and the same thing seems to be happening with that, although not as often.

Any help would be appreciated!

Thanks.