for several reasons
1) My parents make me get off at midnight, so sometimes i cancel so i can get my d/l finished in time.
2) My sister uses P2P too, so there are some BAD files in my shared folder that i kill uploads every chance i get. Boy Bands dont deserve to get shared.
3) My DSL line has a security function that only allows it to be connected 2 hours at a time, to make it less vulnerable. so it might be just then when i gotta disconnect.