For the record, by removing the sprintf lines:
sprintf(tmpstr, "%X",(NVRAM_ADDR + (i * DATA_FLASH_SECTOR_SIZE)));
sprintf(TxSplrBuf1, "%s %s\r", tmpstr, msg);
from different spots in my code and adding a routines to do the conversions, my problems went away.
I use sprintf other places in code without problems. I am running low on FLASH ROM, though I have plenty of RAM. I don't know it that is part of the problem.
Thanks for the help.