Maybe this will help some of you guys who get error messages during map validation or installation itself.
Recently I was playing with my Sandisk 8gb MicroSD card which I have always been using to update my UC`s Garmin maps.
I did format this card using USB adapter under windows multiple times, using different file systems and different cluster sizes in hope to get it visible for UC`s File Manager from the hidden menu (still no success here :-D)
A few days ago I wanted to install 2014.20 NTU Europe and first time in my life I got those error screens during map validation.
Just before that happend I formatted this card under windows (full format - not quick) as FAT32 4096bytes per sector.
I tried the older mapset from my HDD just to try if it`s maybe caused by 2014.20 files which I downloaded from the web and no, I still got the same errors even whith maps which previously were installed flawlessly.
What I did is I took my MicroSD from the USB adapter, put it into standard SD adapter, and I formatted it in my Sanyo camcoder (full format). After that I deleted DCIM folder which Sanyo has created and put Garmin folder with 2014.20 mapset on it.
Now it works like a charm.
So it seems UC is very sensitive in this filed.
Maybe you guys should try to format you sticks in some simplier devices as cameras, camcoders, dvd players, routers etc ...