To what folder is it downloaded?

Does it come from a recognized/trustworthy website? Does the path show in Firefox's downloads list (Ctrl+j)?

If you look at the contents of dlg.zip, can you associate it with a particular add-on?

In answer to your question the dlg.zip file which internet download manager catches and downloads contains the same files as are found in the dlg.zip folder in the Firefox installation folder and no these files are not associated with any particular add on or extension

What folder do you mean when you say "the Firefox installation folder"? I've searched around two different installations of Firefox 14 (one on XP and one on Windows 7) in both the Program Files folders and my profile folders, and I don't see anything named dlg.zip.

What files does dlg.zip contain?

It is the Dialogs Folder in the Firefox Installation folder in Programs (X86) on the C Drive, it is an exact replica of the Dialogs folder, I have provided you with a screenshot which is a png file that will open in Paint. From what I can tell the files are exactly the same as what is already installed.

Those folders seem to be related to a Conduit "community toolbar" add-on. If you check your add-ons list, do you have such an extension?

orange Firefox button or classic Tools menu > Add-ons > Extensions category

The list is alphabetical within two different groups: enabled and disabled (grayed out).

It's the Winzip Community Toolbar, I disabled it and hope that solves the problem. Thank you for your assistance.