iTunes andor Macbook Pro Wont Recognize iPhone 3G I just bought used

OK. Heres a weird one....
Tonight, I just bought a used iPhone 3G and its in really great shape and seems to be working fine
EXCEPT I tried plugging the iPhone into my Macbook Pro and it is not recognized by either iTunes or by my Macbook. Ive tried 3 different USB cables and rebooting several times and nothing works.
Im noticing that I can plug the cable into the USB power adapter to charge it but it seems to take several seconds before it begins charging. That doesnt seem right.
One thing: it appears that this iPhone I just bought has been jailbroken. Could that have something to do with why my Macbook or iTunes wont recognize it and if so, is there a way to completely reset it back to normal iPhone default settings and use it, UN-jailbroken?
Please help!!!
Thanks,
Kevin
put the charging cable in
iPhone OS 3.0