Ever since stopped running after re-running Redsn0w.
iPhone Dev team has just released a new version of Redns0w 0.9.10b3, which fixes the problem. They have provided the following information on their blog:
The b3 version of redsn0w fixes a problem where re-running redsn0w over an existing jailbreak would cause MobileSubstrate-based apps to stop running until MS was installed again. Now you can re-run the redsn0w jailbreak step without worrying about that (but still remember to de-select the “Install Cydia” option if it’s already installed).
They also have the following tip for users who may have hit "no identifying data was found" while using Redsn0w:
TIP: If auto-detection fails and redsn0w tells you no identifying data was found, you can always pre-select the appropriate 5.0.1 IPSW using “Extras->Select IPSW”.
You can download the appropriate iOS 5.0.1 firmware file from this link for Windows.
In case you need help, you can checkout our step by step guides to perform untethered jailbreak using Redsn0w, which have also been updated with the latest download links: