Itunes syncing problem....2nd time...???

[Ice9812]

Hi,

Last week after i upgraded to 2.1 and used quickpwn to jailbreak and everything was fine ..but then i connected to iTunes to sync some new ringtones and music and about 3 seconds after i hit sync my phone would reboot...... but it sync all my songs and ringtones no problem brfore...

so then i restarted everything computer phone and loaded itunes ...still same thing....

so then i took my girlfriends phone which i upgraded and jailbroke the same way and her phone syncd the new songs and ringtones no problem....

so last week or so i was told to do a restore....so i did....
restored to 2.1..
loaded all my songs and ringtones on...
jailbroke withe quickpwn...
installed all my apps and winterboard themes....
everything working fine.....
until today... everything works fine on the phone no problems at all....i made some new ringtones loaded iTunes hit the sync but and it sent the phone to a reboot in about 3 seconds...
so i got my girlfriends phone and again hers sync the new ringtones no problem....

So can anybody help me i really dont feel like doing a restore everytime i want to add new songs to my phone or new ringtones...i know i can add ringtones through winscp so thats no problem.....but i still want to be able to sync my phone to itunes ....its very frustrating

i dont really have many apps installed:
cydia
installer(which i dont use)
winterboard
cycorder
snapture
flashlight
ireboot
iblacklist
bosstool
thats it for apps

Thank you

anybody?....noone with a similar problem....it really sucks only be able to add new songs or ringtones after a restore and as soon as i jailbreak i cant sync anymore...please help!!!