Television viewers and radio listeners in Exeter are understood to be experiencing signal problems.
City residents have reported that their Freeview sets and digital radios suddenly went blank at the same time every evening so far this week.
But nobody is sure why it's happening, how widespread the problem is, or how long it will continue.
Morris Ferris, 86, of St Thomas, said: "We were watching television just before bedtime, and then the picture disappeared without warning. Then our radio didn't work either. It's happened every evening this week at around 10.25pm.
"This morning was the first day this week I haven't had to re-tune the channels. It's not too bad for us, but I worry for people who are elderly or living on their own."
One resident of Manor Road, St Thomas, said they lost television signal for the first time at 9pm on Sunday and then at a similar time on Wednesday. It came back on at around midnight.
He said: "There has been no notification of that happening. We don't know what is going on and why our signal went out.
"But it is frustrating to have happened twice already this week. Especially as no-one told us about it."
A Digital UK spokesman said it was difficult to comment on individual problems as they can be the result of any number of things – including local interference, high air pressure and people's individual equipment.
In apparently a separate incident, a number of Exeter properties were hit by power cuts for five hours today due to engineering work in the Dunsford area.
The transmitter went off air between 8.07am and 1.12pm, while the planned work was carried-out.
The spokesman said: "Due to planned electrical engineering works at the Dunsford local relay transmitter, TV and radio services were temporarily off-air from around 8am this morning for some viewers. "We have been advised by the mast operator that work has been completed and services are now broadcasting normally."
If you are having reception issues, please call the Freeview Advice Line on 08456 505050.
