php system call problems

Using something like...
system ("C:\\cool.exe C:\\coolfile.cfl", $returnVal);
simply does not work, and simply gives a returnVal of 1. Nothing in the php error log even with all errors turned on, nothing in the system log, and a "file not found" error returned by using some suggestions from the system documnentation page (something like echo system("(".$SysCmd." > /dev/null) 3>&1 1>&2 2>&3", $Ret);). I tried a million combinations, and they worked on the cmd line, but failed with system.

Solution?
system ("C:/cool.exe C:/coolfile.cfl", $returnVal);

My new rule is to always use forward slashes with system.