Two scheduled tasks - one runs every time, the other only sometimes

running vista home premium 32bit sp2. have 2 scheduled tasks, each launching .bat file, 1 set run @ 5:00 pm every day, other set run @ 11:00 pm every day. 5pm task runs every day without fail; 11pm task runs of time, @ unpredictable times fail launch. when fails, task scheduler shows last run time = [last time ran], last run result = operation completed successfully. (0x0), status = ready, , next run time = [blank]. if select task, right-click, open properties, , click ok, next run time changes [tonight @ 11:00pm] , task run -- continues working 4 or 5 weeks, fails again after day or two. once task has failed, never run again without type of manual intervention.

the computer always powered on , logged on both @ 5:00 pm , @ 11:00 pm, time of day cannot reason failure.

settings same on both tasks:

• general|user account -> mycomputer\me
• general|run whether user logged on or not -> true
• general|do not store password -> true
• general|run highest privileges -> true
• general|hidden -> false
• triggers|daily; @ [time] every day; enabled
• actions|action: start program; details: c:\[filename].bat
• conditions|start task if computer on ac power -> true
• conditions|stop if computer switches battery power -> true
• conditions|[everything else] -> false
• settings|allow task run on demand -> true
• settings|if task fails, restart every -> false
  
• settings|stop task if runs longer -> 4 hours
• settings|if running task not end when requested, force stop -> true
• settings|if task not scheduled run again, delete after -> false
• permissions on 2 batch files identical -- , not expect related problem; can't see how permissions problem permit file run of time, cause fail occasionally
• both batch files located in same directory (c:\)

settings different:

• settings|run task possible after scheduled start missed -> false task works, true task fails (originally, both false, , set true failing task in hopes of fixing problem, no avail)
• action|edit action|program/script -> task works has 7-character filename (c:\abcdefg.bat), task fails has 9-character filename containing underscore (c:\ab_cdefgh.bat)
• action|edit action|add arguments -> task works has no arguments, task fails has 2 arguments: 7 letters, 1 letter, separated 1 space. there no quotes or other special characters in parameter string.
• action|edit action|start in -> task works, blank; task fails, c:\ (no quotes). 

what in world going on here? 1 obvious course of action make settings different same, , see if fixes things. can't delete parameters task has them, though.

any ideas? i'm @ wit's end.

solved.

the vista task scheduler apparently has problems task *names* longer 7 characters. changed name of task, , no other attributes, 9-character name 6-character name more month ago, , has been working flawlessly ever since.

here's additional information others might struggling same issues , receiving same useless "advice" microsoft see in andy qi's response above. if go original post in thread, you'll see had 2 tasks, 1 worked every time , 1 intermittently -- , apparently randomly -- failed. examining windows logs, traced intermittent failures shutdowns of task scheduler service. never able determine reason shutdowns, did determine when scheduler shut down, failing task (with 9-character name) not rescheduled. every single time.

i made numerous duplicates of non-failing task, changing time of day , name of task, giving them names mytask08, mytask009, mytask0010, mytask00011, etc. numbers indicating length of name, through ...0018. enabled of them, , waited each 1 of them run @ least once, , have scheduled next-run-time listed.

then shut scheduler down, in apparently way so: rebooting computer.

less half of them rescheduled when scheduler service restarted: mytask08, mytask00011, mytask0000013, mytask00000014, , mytask000000000018.

mytask009, mytask0010, mytask000012, mytask000000015, mytask0000000016, , mytask00000000017 not rescheduled.

once again -- differences between these tasks names, , time of day run -- within window of 20 minutes. pattern of tasks rescheduled, , ones not, has remained consistent across multiple reboots. tasks names less 9 characters long, or 11, 13, 14, or 18 characters long, rescheduled correctly every time, , tasks names 9, 10, 12, 15, 16, or 17 characters long not rescheduled. every time.

the conclusion pretty clear: there's bug in vista task scheduler prevents rescheduling existing task when scheduler restarts, based on no factors other length of name of task.

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