Well, Jailbreaking any device has its own share of risks. Even though lots of people celebrated the Dev-Team finally releasing a fully untethered jailbreak for iOS 5.0.1, many of the people that used it were already rocking the past version that allowed a tethered jailbreak. Many of these users ran into trouble because the jailbreak would case MobileSubstrate-based apps to stop running.
The good news is that all this is a work in progress. The Dev-Team has just released an updated verso Redsn0w, which is now 0.9.10b3 and fixes this problem. According to the post:
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).