If you're unlucky enough, you may have sampled a pixel like the one shown above in After Effects. While 32-bit floating point mode has brought us linear color space and overbrights, it does have a hidden dark side. Negative pixel values can be perplexing, but seeing a NaN (Not a Number) or inf (infinity) floating point value can really make your head spin.
These things can cause all kinds of problems if they find their way into a comp. After Effects has safeguards to prevent them from being created, but they can slip in if your renderer burned them into a floating point format such as OpenEXR.
If you see one of these things, the first thing you should do is write an