Web Search; https://www.google.com/search?q=Amozilla&ie=utf-8&oe=utf-8&client=firefox-b

Entries claim Malware.

You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Is there also a aMozila or aFirefox folder in the secondary location in AppData\Local ?

You can remove this folder as it isn't used by Firefox.

Thanks for your replies.

There is an AMozilla folder in AppData\Local too. I hadn't looked there at first. Only saw it in Roaming.

I will remove both, I guess, but was this ever a legitimate folder?

FredMcD, yes I saw some of those forum conversations, but nothing from Mozilla itself addressing the 'AMozilla' phenom specifically.

I haven't noticed any particular performance issues in the last year.

Hi. Just noticed this post - so probably too late to the party to be of help.

Re the "Amozilla" folders, this is the sort of thing that might have been done by a support admin whilst fixing an issue. I.e. create a new profile and then rename the old with a leading "A" so it's still there but inactive. I've seen that done by professional IT support a few times - even done similar myself occassionally. Of course, you never "get back" to cleaning the old, now redundant, folder/file up... Or it might be malware just possibly - unlikely if nothing picked it up and your system ran ok.

Either way, deleting it was fine.