SSIS: Why do columns become misaligned when importing flat files?

Hi All

I am stumped with the following.

When I try to load a fixed length flat file into a table, the first few thousand records load correctly but then the columns start going out of sync.

Visually it looks like the data is drifting off to the right. Below is what the table looks like when the load completes:

Col1    Col2    Col3    Col4

--------------------------------

1        1         1         1

1        1         1         1

  1        1         1         1

   1        1         1         1

    1        1         1         1

      1        1         1         1

        1        1         1         1

Additional info:

1. The file has 400 000 records.

2. The first few thousand records load OK.

3. Source file is a flat file, fixed length, no delimeters.

4. All rows are same length, with LFCR.

I tried using a script task to check with C# if all rows are the same length and has the same line terminator, and could  not pick up anything out of the ordinary.

What could be the cause?