dmg files fail to mount
 

Recently, about 90% of the .dmg files (originally .sit or not) refuse to mount on OS 10.3.4 with latest LW Pro. Seems always the case with ******.

Get message saying "no mountable file structures" ????

If you've dld them with a p2p app (such as LW, of course) then there is no telling if the .dmg will work or not, since they were most probably made by an amateur or something (I don't mean to sound snobbish or anything). If you say that 10% of the .dmg files do mount then try dlding .dmg files from the net (try dlding for example VLC player or some other useful app) just to see if you can mount these too (since you're almost 100% sure that these were made by a more professional hand).

making dmg files
 

Yes, I can open SOME .dmg files, but very few on LimeWire. Unfortunate.

Yup, I don't think there's anything wrong with LW. Just that, as I said, many cracked, ripped or whatever versions of application one tries to dld with a p2p app will not work for one reason or another (missing files, unmountable disk images, etc, etc...). You will have to keep dld among the choices LW gives you until you find the right one I'm afraid.

I have another (probably not so bright) idea: if you haven't tried this one yet, then burn the .dmg onto a blank CD (if enough space is available) and then reinsert the CD into your drive. See what happens and post back.