the invalid character for cast specification problem we had only seemed to be on Datetime columns.

first thing we did is remove the data conversion steps in some of the package which were converting varchar to nvarchar. The datetimefields were converted from datetime to datetime.... But removing the conversion to the same datatype did not solve the problem, it did happen a lot less.

It also happens when copying from oledb source to oledb destination without a data conversion step. When the source is not based on a query but just copies a table.

After removing the data conversions we also:

- switched on "Lock pages in memory"

- limited the max memory for sql server

- limited the number of parallel executing packages. We had many packages running at the same time.

Now we haven't seen the conversion error for a while (2 weeks) ... so far so good..