I used to use Fastone too - very good little app.
I am trying to re-edit a picture from a while ago for my camera club meeting next week (actually now finished it). I have been waiting and waiting for LR to build the thumbnails, and still waiting as I type. So I opened ACDSee, located it, made a duplicate, ran it through ACDSee develop, sent it to On1 RAW to finish it off and exited both programmes. Meanwhile LR is still building thumbnails. It is beyond me how this ever got so popular - if it wasn't Adobe and linked to PS I doubt any sane person would buy it.
Update - just been told by LR that all the photos are missing - funny how ACDSee found them all . . .