Re: Rectangular marquee tool is having a problem. I just reformatted my computer and reloaded PS 6. Once I have made my selection with either the marquis tools or other selection tools the fill option works randomly. It will fill once on a document and t

What do you mean by "PS 6"?  Did you mean Photoshop CS6?

Do you have a Perpetual License or a Creative Cloud subscription?

Did you apply all the updates?  What version do you see on the first line of your Photoshop Help - System Info display?

The devil is in the details

-Noel