The GMA and UNL files 'tie' the map to a certain unit, or indeed several units which are entitled to the map thus allowing the entire map or certain portions of it to be loaded from your PC to the qualifying unit via MapInstall. As you've found, without both sets of files the map would be useless on your unit [unless then unlocked with an unlocker e.g. gimgunlock to remove the GMA proctection]. The unl and gma files actually serve quite different functions, but their lack results in effectively the same result. More information can be found here: [Only registered and activated users can see links. ].
Answers to most questions like that can be found in the [Only registered and activated users can see links. ].
I'm of this opinion Pungente: If hard reset/clear NV/reinstall fw/correct reformat doesn't resolve the problem then, and only then as an absolute last resort, go further and defrag etc. This is because imo defraging flash drives does not have the same value as defragging mechanical hard disc drives because the two types work quite differently. Defragging a HDD can only benefit it because by rearranging the data so it is more easily found and thus reduces the time involved in seek heads jumping hither and yon to find it. Flash drives actually place data in different places quite intentionally to enable 'wear levelling' to occur so that as much of the available space is used as often as possible. Unnecessary reformatting 'uses up' this wear levelling and hence the remaining effective life of the drive. Defragging probably has a similar and even more dramatic effect. I believe that's why Giomen added the emphatic 'Be careful!'.
This is an interesting subject, however if it continues here I'll spin it off to another thread. I'm not an expert in this field and the above is a layman's view and opinion.
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