It seems the GDAL upgrade from 1.9 to 1.10 changed the way CSV files are handled so that I now have a non-functioning QGIS. App hangs trying to import csv data file when previously had no problems with this and other csv text files.
I have deleted all data files, all files in the hidden .QGIS folder, all prefs and caches etc yet the app continuously tries to load the problematic file that I have deleted. Even replacing the bad file with another CSV file that works in another project fails to prevent the hang.
So now I have to recreate the project with customised colour schemes and 100s of hours of devt over the last 6 months while QGIS was stable.