-- esri support--
"From the information you provided so far, I understand that you are facing a problem with " Status of the bug# NIM063382".
I really apologize for the inconvenience your facing but the status of this issue is resolved in Arc GIS 10.1 and after having an intensive research at my end and discussion with the Senior Analyst, I apologize that there is no workaround currently available for the same."
After reviewing the notes from development, I believe that this may actually be an intended change in the software to prevent the software from explicitly changing the user's data. It is currently stated as repaired in version 10.1, but it's currently under discussion to implement this in a service pack for ArcGIS 10.0.
Although this behavior will still occur with service pack 3 installed there are several methods to repair your data in preparation for this issue. You can either manually re-add the fields with a supported text field length of 254 characters or less, use python to automate re-add the fields with a supported text field length, create a template from the data and use the simple data loader to append the data into the modified template, use the append tool and specify no test on a template of the feature, etc. Other than this, any gp tool that returns an output in shapefile format will error if it contains a text field with an unsupported field length for the shapefile format.