Notice: This solution only works for EDGE iphones (At least its where I tried it) and its the error 6 when trying to Restore to 2.1 Custom Firmware

Solutions can be the partition size too.
Let it be more than 700 Mb.

But if thats not your solution.
This is the one MickieF told me.

Restore iPhone to 2.1 Original Firmware.
Uninstall iTunes 8
Uninstall Apple Mobile Device Support.
Erase iTunesLibrary.itl
Install 7.6

Restore to 1.1.4
Kick out of recovery Mode.

Open Winpwn.
Pwned ur iPhone with 1.1.4

Go back to iTunes 8
and Restore to custom firmware
in Restore Mode.

Thats All
Thanks MickieF!

Credits for him.

Hope it helps u.
Hernan Sananes - lamanodedios

Dont care about this any more.
Just Restore to 2.1 Original Firmware
and use the new QuickPwn 2.1

Just DON'T restore in recovery or DFU mode.
Click shift+restore and choose the custom ipsw.. it's as simple as that!!!