I solved all my problems.
The error message when importing the specific survey, was caused by the configuration of PHP. The imported survey was to big. I solved this by changing the upload_max_filesize setting in the php.ini from 2M to 20M.
Still the limesurvey error message is quit confusing:
To be able to import and copy my survey (earlier imported from 1.87) I still had to solve my character set problem. I first changed the driver back from 'odbc_mssql' to 'mssql_n', as the odbc driver gave lots of other troubles. Then I adapted the PHP configuration by changing the mssql.charset parameter to UTF-8. This forced freetds to use the UTF-8 character set.

After this my limesurvey installation was working properly with new created surveys. My existing survey (earlier imported from 1.87) was still giving problems. Therefore I had to replace manually all strange characters from the export file (.lss). Because of my chracter set problem all the special characters like ë, ï, é,`,ö etc. where misshapen.

Hello,

This post is old but I resolve the same problem by simply inscrease:

upload_max_filesize

in php.ini. In my case I put 10M (10 megabytes)

Hope that help someone!

Alan