Hmmm. I'm chasing the same problem, I think. Are you working on Windows Schedlgu.txt (task scheduler) log file?

I'm considering a few options
1. Brute force solution -- delete the file after each check. If I need to keep the data, write it off to another file.
2. The lazy admin solution -- Have Windows notify you when Task Scheduler can't run a task. See http://support.microsoft.com/kb/308558. Of course, this requires faith that Windows will actually do what it says it will.
3. The whole thing solution -- check the whole file for failure s each time. One of the end users I'm supporting suggested this.
4. Time and date solution. Look for the appropriate time and date a task should run and get the matching log entry.
5. Perl Watchmaker's solution. Use Win32::TaskScheduler. Very fine-grained control. Do you need that much?