RTEMS time overflow problem

[Nasim Zehra]

dear users
   also tell me that if i select periods of tasks such that when they are executed ,they are in running condition and before they are deleted ,time over flow error is occurred.Is there any solution for that.
i am having four tasks
1st--------executed in 2202 ticks
2nd-------// //            848
3rd-----------------------246
4th--------------------88
 above mentioned ticks are equal to execution time of respective tasks.
now i am selecting periods for them randomly so that upper bound condition for 4 tasks should be met according to rule of rate monotonic schedualing.like that
 1st---------8000 period in terms of ticks
2nd---------3000
3rd---------2000
4th---------5000

using these periods my U = 69.85%
while theoritical U= 4(2(1/4) - 1)= 75.682%
 so 69 %<75%
=> tasks are scheduable.
but implementing it causes ime oveflow error on T simulator for leon3 processor.

kindly help out.

regards
--------
nasim