Take a break - it's amazing what a fresh mind can see.

I'm not familiar with REGEXP, so can't comment on that.

I would strip down the query then build it back up one argument at a time, to see where the problem is. Do you get some records from the query select * from nsmw? If so, then add your where clauses one at a time. This will, at least, narrow your focus a bit.

update: a quick look at REGEXP turns up this for MySQL 5.1:

The REGEXP and RLIKE operators work in byte-wise fashion, so they are not multi-byte safe and may produce unexpected results with multi-byte character sets. In addition, these operators compare characters by their byte values and accented characters may not compare as equal even if a given collation treats them as equal.

Are your strings plain ASCII or are they multi-byte?