Hi walpow,
I was able to login, and it looks like this PHP error was being produced (perhaps you weren’t logged in as a superadmin on the front-end, and weren’t seeing it?)
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 30674 bytes) in ../mod.weblog.php on line 548
So, it looks like too many entries are simply being pulled. This would also explain the somewhat erratic behavior.
We think an easy fix would be to use the search= parameter in your weblog tag to check for an empty writer-blurb (instead of just hiding entries with the {if writer-blurb} conditional).
Give that a try and let us know how you fair.