They just released a new version of greenpois0n for mac. I can confirm it is working for 4.2.6. Just jailbroke mine.
Perhaps thats the issue. I used the one they just released for 4.2.1 on Windows.
I just downloaded and installed the new GP for Windows and JBd my phone no problem.
I think cydia is over loaded with all the users now. I've had problems with cydia for a couple days now.
That could be it. I'm actually doing a restore/rejailbreak right now. I do remember that when I first launched Cydia it prompted me to do an update. It started installing but I received a text and not thinking I hit reply. I think I may have corrupted things halfway through the install, so I'm going to try that and report back.
jailbreak was quite smooth but terminal will not stay up to change password. . .help?