Those of you who have been experiencing bugs after using JailbreakMe will be glad to find out that Comex made some fixes to the kernel patches for the userland jailbreak, and these fixes have been pushed as an "Essential Upgrade" in Cydia.
To get this update, simply launch Cydia and you should be prompted to upgrade. Make sure you do not run JailbreakMe again over your current jailbreak. Instead, let Cydia do the job for you...