I know this is way late, but just for the record:

It's a known problem with the M275 Tablet PC. The engineer from Taiwan came up to our campus and showed us the embarassing fix.

What happens is that over time, a misplaced piece of metal can make contact with the Tablet's digitizer, and short it out. Simply placing a barrier in between (Mylar Tape) will resolve the issue, but it requires opening the screen enclosure. It's really easy, about 5-10 minutes to fix if you have the tape and tools. But I don't recommend it for a beginner.

If someone needs it, I could possibly provide a link to how to fix this, including video, if it is still on our webservers.