7 On Your Side has dealt with disappearing rebate checks and reappearing telemarketers, but this was the first time we had tackled this type of unexplained activity.

Claudia Gerst showed us the mystery of her kitchen floor.

"The very first X was right here and I saw no other X's. Within the next year or year-and-a-half, another one appeared, then another one," says Gerst.

Gerst had new kitchen vinyl installed back in 2003. About two years later, the X's began appearing and new ones are showing up all the time.

Gerst's friends have guessed it was a poltergeist. There has been speculation that UFOs are involved. That's why we asked Bob Corridan to check things out. He's not a paranormal investigator, but he does own San Francisco's Linoleum Larry's.

Finney: "What is it?"

Corridan: "I believe it's a felt tip pen that they marked off the panels as they stapled off the underlament."

Finney: "So where was the mark made?"

Corridan: "On the plywood itself."

A good floor installation, and this is a good installation, usually has underlying plywood. Sometimes that plywood is marked.

Finney: "Her description of it slowly coming up like a poltergeist, is that how it would work?"

Corridan: "Sure. It's migrating to the top. So that ink is pulling itself up."

The Conklin Brothers flooring store in San Leandro installed the vinyl, but it had been sold. The new owner had nothing to do with the installation, but still he tried to get the manufacturer to replace the floor, but no go.

It turns out different Conklin Brothers stores have different owners. An installer was sent out by the owner of the San Jose, Fremont and San Mateo stores. The San Jose Conklin Brothers folks, who were in no way involved in this sale or installation, nonetheless jumped in and got the job done.

This time Gerst picked a different color, but the same pattern for her new floor.

Gerst: "Yeah, yeah, I love this floor."

Finney: "I am glad it worked out for you."

Gerst: "It really, really did and I am very, very grateful."

We really want to thank the Conklin Brothers out of San Jose, San Mateo and Fremont.

More information:

Linoleum Larry's -- 415 921-4937

Conklin Brothers -- www.conklinbros.com