OK, I'm guessing that you're using CodeWarrior for ColdFire 6.4. What version of CodeWarrior made the project that you're working with? It sounds like you're having a file path problem (that is, the information used to find header files in the directory trees).
First, check and see if the source file you're working with doesn't have a directory path--or part of one--hard-coded into it for stdlib.h. If it does, edit that out. If not, proceed a follows:
1) Make a copy of the old project directory and all of its files.
2) Open it with CW ColdFire 6.4.
3) Choose Remove Object Code.
4) Choose Reset Project Entry Paths.
5) Choose Re-search for Files.
6) Try building the project now.
Steps 4 and 5 essentially purge the project of its old directory tree info, and forces the IDE to look for these files again. The reason for making the duplicate project is in case this attempt makes things worse, you can always start over with the old one.
---Tom