The error you may see is Mobile Substrate Safe Mode. According to Saurik it has to do with Winterboard
and the update of Mobile Substrate in Cydia. This was needed to get many applications compatible with
firmware 2.1. The text full of pop-up error that appears is as follows:
A recent software installation, upgrade, or removal might have been the cause of this. Your device is
now running in Safe Mode. All extensions that support this safety system are disabled. Reboot (or
restart SpringBoard) to return to normal mode.”
The solution for this issue is simple. Just reboot your iPhone and all will be ok again. Saurik is currently
working on a fix so no worries.