Fnord Software has a new free plug-in, NaNny, that fixes over-bright pixels turned black in OpenEXR, TIFF, and other float files inside After Effects. Float space is a strange place, where bugs can result in NaN (Not a Number), inf (infinity), and negative pixel values that can wreck havoc with image processing. Pictured here is the sample EXR with a blur filter applied; without NaNny you just get the black block.
Plug-in author Brendan Bolles provides good documentation on his blog and in the ReadMe file that helps explain things. NaNny doesn’t do anything about negative pixels (often a result of color space transformations), but Brendan includes a tip to deal with them.