Unfortunately there is a new bug in the Row Filter node in KNIME Ver 1.3.5 (it hasn't been there in earlier releases):
When you select "regular expr. pattern matching" as matching criteria in the Row Filter's dialog, it ignores the checkmark in the "case sensitive match" checkbox, performing always a case insensitive match.
To work around this, you could use the String Replacer node to replace (case sensitive) the value you want to filter out, and then actually filter out the new pattern with the Row Filter:
In the flow, insert the String Replacer node, as predecessor to your row filter.
Let's assume you want to remove all rows containing "KNIME", but all rows containing "knime" should stay in the table.
Configure the String Replacer to replace all values "KNIME" with a value that otherwise doesn't appear in that column (for example "_this_must_be_removed_"). Make sure to check the "Case sensitive search" box. (In the String Replacer the case sensitive match actually works...)
Now, feed the result table into the Row Filter. Exclude all rows that contain "_this_must_be_removed".
We apologize for any inconvenience this may cause.