may be you should set on property of the tempdb , truncate log on checkpoint .
the other method is increate the size of tempdb .
i don't know the program of your system , may be some dead lock occured in your system , when the system is running , you can check the lock status of system .
the other reason may be you use some temp table then leave them in tempdb after you finish one work , you should check you code to prevent this type of bug.
sorry to reply with english , my hinese input system have some bug now .