Absolutely off the top of my head, knee-jerk: Carryover of Color Developer into the Bleach-Fix. Are you using a Stop Bath between them?Originally Posted by inthedark
Another, but somewhat more remote possibiltiy would be a random temperature variation between the "raw" paper and the Color Developer - If you are using a drum, are you allowing an adequate dry "pre-heat"?
Now, finer - a few questons:
How are you processing, drum, tray (!!) or? Are you using some sort of processor, and what RA-4 Chemicals and paper?
Another possibility is "fried" paper, out-of-date or improperly stored at a relatively high temperature. This usually shows up as yellow-browning at the edges, migrating toward the center of the sheet - but it is possible that it may be random. Do you refrigerate your color paper in storage?