I recommend that you reload the original rgn file. It was backed up when you ran memap. So, DELETE the file 017901000320.rgn (this assumes your firmware update was 320). RENAME the file 017901000320.bak to 017901000320.rgn and run the Garmin updater again.
When you originally created your modified file with memap, you *may* have made a string too long... that could cause the screen shift.
-Taz
If you can't beat your computer at chess, try kickboxing