I have been trying to simulate what you have done and to no success. I have been using DTS for the past three months migrating our old system to SQL and no problems.
I tried changing a date to string the placing invalid characters into a string and then opening my DTS package, and closing (no errors, errors only appear when I run the package).
maybe a few more details, e.g. is the source a SQL table, access table, excel etc, what is the destination, are you using meta dat etc.