Well I got to ask the obivous... Did you back up your files and perform a hard reset yet? If that did not work have you tried the manufacture website and look for any updates? If you are still stump'd try www.pocketpcthoughts.com and ask around.
Well it would be in your instructions or you could google it. or the easy way to do it (IF YOU ARE NOT USING WINDOWS MOBILE 5) is to let the battery run dead, then charge it back up - MAKE SURE YOU DO A BACKUP FIRST, YOU WILL LOSE EVERYTHING THAT YOU LOADED. also try the link I provided.