The same with rownum < or using top 99 works just fine. So, not sure if this is case issue.

Are you using 2008 R2 SP1 64bit against Oracle 11.1.0.7 64bit as well?

I found a workaround to use the ODBC drivers instead of OLEDB but will have to monitor performance. Thought that OLEDB.Oracle should work fine but nothing yet.