[CentOS] [OT] Firefox loses plugins, anyone else? Bug? Known?

> Fully up-to-date CentOS 5.2 and Firefox browser. A previous thread had a
> problem with plugins disappearing. I've discovered, by accident, a
> causal relationship.
> 
> Running a Thunderbird mail client (could happen with others? Haven't
> tested with Evolution yet.) I click a link that opens the browser. BANG!
> The plugins.dat is "emptied".
> 
> Restored from my rsync backup, repeat, BANG! "Empty" again.
> 
> Now, if the browser is already open, NP.
> 
> Anyone can confirm?
> 
> Known problem?

Are you using a 64-bit firefox by chance?
I have a similar problem with flash plugin. Try to reload a page or
restart the browser. This works for me.
I didn't look any further as I thought this to be a problem of
32-bit flash plugin with 64-bit browser.

HTH