i have an iphone 3g,which i had 3.1.3 firmware jailbroken for the longest time. i recently upgraded to 4.1 and jailbroke it,it was so slow that i just restored it. i was reading about downgrading back to 3.1.3. my problem is i cant get into dfu mode for nothing.i never had a problem till i restored it. i can easily get in dfu mode on my wifes phone,but mine will not do it. ive tried everything even ziphone 3.0 and it wont do it. when i had it jailbroken at 4.1 and it was slow and freezing i would hard reset it by pressing the sleep and home button till it reset but i cant even do that now. both my buttons work fine otherwise. any info would greatly be appreciated.