When Don Relyea, a Dallas area computer programmer, attempted to vote on an electronic touch screen machine, he got a bit of a surprise. The machine changed his vote.

And when Relyea posted a video of the voting machine error online he received another unpleasant surprise. A Dallas election official threatened to investigate him, saying that any video taping in an election booth is illegal.

“It looks like a hoax,” said Bruce Sherbert, Dallas County’s election administrator after viewing Don Relyea’s tape. Sherbert added that he planned to ask the Dallas District Attorney to investigate Relyea.

However, Alex Halderman, a computer scientist at the University of Michigan who has spent years studying voting machines, was surprised by Sherbert’s reaction. “This is a known class of problems with touch screen voting machines.”

Hear about it on today’s episode of the Marketplace Tech Report.