>Most of the troubles I've had with the scheduler arose when the program uses logical drives. You can solve this by wrapping the .exe into a .bat file and "net use" the logical drives before you call the program.

Also, the environment in which the task runs is that of the account it's running as, with all the settings and rights belonging to that account. Also, the folder in which it runs is probably %system% unless specified. So it may run perfectly when run as-is, and run into many obstacles when running as a scheduled task. Full of gotchas in there.