Firmware: SD browse to directory issue

[SpudsterZ]

Machine Atari 800 w/ Incognito set to basic Colleen mode.

Scenario

Browsing to a particular directory:
1. White light solid, orange light solid
2. Pause
3. Both lights out
4. White light on
5. Longer pause
6. ![ERROR OPENING DIRECTORY](https://user-images.githubusercontent.com/74847414/99896101-dce70480-2c52-11eb-9e21-001226a849dc.png)

Must ESC back to main - all other options fail (N/F/DELETE/OPTION).

Directory details

338.1 MiB (354,516,013)
11,166 files, 0 sub-folders

Feedback Clearly an extreme case - minor issue. A more obvious error condition would be helpful. Gold star for forcing user to return back to main or recovering from error so other options function (i.e. up directory).