Yes. You do not want to go back to 5.1. That is not jailbreakble.
What I would do if I were you:
2) I would download the 5.1.1 iPSW file for my device model (download from Mozilla Firefox or Google Chrome. NOT Internet Explorer) and save it to my desktop.
2) Then I would enter DFU mode, open iTunes, and shift+restore to 5.1.1 iPSW.
3) after restore I would "setup as new" and not restore from a backup..especially the most recent one(you can restore from backup if you want but I don't recommend it. It is wise to not restore from a backup when the reason your restoring is to fix a problem...your better off to choose "setup as new")
4) After setting up as new and not restoring from backup I would then wait for iTunes to finish its initial sync. After the initial sync is done...close iTunes.
5) Then I would jailbreak with Absinthe. Do not touch the device until Absinthe tells you it's okay to open Cydia.
6) once the jailbreak is done, I would open iTunes and sync my apps, music, tones, etc before opening Cydia.
7) Then I would open Cydia, let it load completely, I would select my User preference which would be "Developer" and not "User" or "Hacker".
8) Once Cydia has fully loaded I would then tap on the Search tab and search for "Mobile Substrate" and install it...nothing else. Just Mobile Substrate.
9) Then I would Install iFile. (buy it. It's worth it)
After that I would start installing my tweaks..and be extra careful as to what I install, making sure that everything I want to install is compatible and not going to conflict with anything else I may want to install.
ok. i did all of this and now i have no service. in diagnostics & usage i have "lockdown 2012-06-01-19043" what have i done?