Weird Tungsten E2 problem - won't turn off.

I've had my Tungsten E2 about a year. It hotsyncs fine, accepts data and displays data fine. I didn't add any software recently (there is 3rd party software but it's over 6 months old). I didn't even drop it. But, starting 2 days ago it won't stay powered off. After I switch it off, after 10 seconds it's back on again! It does this with or without the power cable. Without the power cable plugged in it powers down in a day. And it won't do a hard reset. I ran antivirus software on my PC but it says it's clean. The Palm website doesn't say anything about power staying ON. Any suggestions would be appreciated. Thanks.