In B1 I have =if(A1="this","that","") and continuing down b:b

i then copy b:b and paste special (value) into c:c

I have a sumproduct equation that runs off c:c. the problem is that
apparently the blank cells ("") arent really blank. I get a #VALUE error.
How can I find all the blank (''") cells and clearcontents?

Thanks in advance
jeff