In order to fix the errors in beta 1 and beta 2 versions of RedSn0w iPhone Development Team released the new version of Redsn0w 0.9.10b3. New release includes necessary fixes for the issues found in 0.9.10b1 and 0.9.10b2 during untethered iOS 5.0.1 jailbreak.
Following is the paragraph from official 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).”