Morgan, do you have a fax? If so I'll send you a page from a previous printed manual from CCS, regarding problems and limitations when calling functions from an ISR function. For unknown reasons they seem to have omitted that page in current manuals. Mail the number to me privately. I have been using CCS for 8+ years and it has served me very well (for a number of commercial products). I continuously by the maintenance.You just have to remember that a PIC is not a PC and hence you should not expect this from the compiler either. Regards, PerL -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist