1490T shuts down

No, the 14xx (and 13xx) series with the various software updates are normally extremely stable. Neither my 1310 or 1490 have shut down unexpectedly for well over a year. I'd suggest a hard reset to see if that cures it.

Agreed. My 1490T has shutdown before but it is very rare.

No, the 14xx (and 13xx) series with the various software updates are normally extremely stable. Neither my 1310 or 1490 have shut down unexpectedly for well over a year. I'd suggest a hard reset to see if that cures it.

I tryed a hard reset (power on pressing right bottom corner), I selected again location, etc, but the problem remains. Also, some areas, with zoom in 8 km/cm ONLY, are drawn in green with no inside details. Very weird!

No, the 14xx (and 13xx) series with the various software updates are normally extremely stable. Neither my 1310 or 1490 have shut down unexpectedly for well over a year. I'd suggest a hard reset to see if that cures it.

Supposing that it is a soft/firmware problem (and not a hardware), is it any procedure to reinstall ALL the operating system? Thank you

In my experience issues like this are a result of improper removal of the device from a computer resulting in filesystem corruption [Note: early versions of the 13xx/14xx models had a firmware bug that could result in corruption by themselves]. One should always eject/remove the GPS from whatever OS they're using before physically unplugging the unit. Failing to do that can result in partially written files and/or corruption of the filesystem. This is a generic issue with any removable drive and has nothing to do with Garmin.

Now as to your question it is possible (I've done it) to copy all files from a unit, reformat it, and copy everything back to fix such issues. That said I would not recommend doing this unless you know what you're doing and are willing to brick your unit (and have to return it to Garmin for repair).

In my experience issues like this are a result of improper removal of the device from a computer resulting in filesystem corruption [Note: early versions of the 13xx/14xx models had a firmware bug that could result in corruption by themselves]. One should always eject/remove the GPS from whatever OS they're using before physically unplugging the unit. Failing to do that can result in partially written files and/or corruption of the filesystem. This is a generic issue with any removable drive and has nothing to do with Garmin.

Now as to your question it is possible (I've done it) to copy all files from a unit, reformat it, and copy everything back to fix such issues. That said I would not recommend doing this unless you know what you're doing and are willing to brick your unit (and have to return it to Garmin for repair).

Well, Stuart, may be not now (I have only this unit) but may be later I am willing of doing a "hot" reinstall. What would be the procedure? Where can I find the original files? I have a quite decent instruction in electronic and computing (Electronic Engenieer, working in stuff, no papers :)
Thank you

Ok, but don't blame me if your unit is toasted or if the issue isn't fixed. I'm not a Garmin employee so this is my own advice.

1) Plug the unit, via a USB cable, into a computer.
2) Copy all files/folders (there are hidden ones) to another drive (you might keep these as a backup).
3) Reformat the 1490T as a FAT32 filesystem. After this it should be totally empty. Do NOT remove the unit from the computer at this point!
4) Copy all the files, saved in 2) back to the unit.
5) Eject/remove the unit and then unplug it.

FYI the 1490T has about 2GB of files so the above can take some time.

The above assumes that the files already on the device are good (not corrupted). That may or may not be true (and difficult to determine). The issue may not be fixed if due to a corrupted file. That said any filesystem issues should be repaired.

There is no place to get all files but many optional ones can be (re)loaded by using Garmin's WebUpdater.

BTW I'm a (semi)retired Electronic Engineer (with papers) ;)

Ok, but don't blame me if your unit is toasted or if the issue isn't fixed. I'm not a Garmin employee so this is my own advice.

1) Plug the unit, via a USB cable, into a computer.
..................................
BTW I'm a (semi)retired Electronic Engineer (with papers) ;)

Thank you, Stuart. Also I try to be semiretired, but allways there are something to do...
I suspect that some file/s is/are corrupted, so probably, the procedure you described could be of little help.
Also, I made an update with WebUpdater to V6.20 some time ago.

Is any way to "force" the unit to re-update? I tryed to do that, but it seems that the Nüvi "remembers" that it
was updated previously, and the prodedure can not be completed, I think. In some site I read of deleting some
file to force the update.

I can live with this issue, and in few months I plan to go to NY, so I can buy a new unit (I live in Buenos AIres: units
are quite expensive) and give this as a gift to some relative less perfeccionist ;)

Is any way to "force" the unit to re-update?

WebUpdater allows you to reload he current firmware (6.2 in your case). It doesn't allow you to reload optional files--they have to be deleted from the unit first.

Another idea is to perform a master reset of the unit (will erase all user data so backup first).

....
Another idea is to perform a master reset of the unit (will erase all user data so backup first).

Already did it and no change.:(