Sounds like something going wrong with the date formats when reading the file. Can you see the same problem in a simple QVW file that reads the same data source?
Make sure you read the date with an explicit conversion, such as
Are some of the dates left aligned in a list box - this would imply that these values are strings, not dates.
For more detailed diagnosis I suggest that you post a sample of the source data and QVW that illustrate the problem.