A green tinge and other picture quality problems are often due to the quality of the HDMI cable you are using: Cheaper cables are usually of a poorer quality than more expensive ones, which often leads to poorer picture quality.
An incorrect screen format may lead to a green tinge. For CRT televisions, select the “4:3 Standard” screen format. Then restart your TV set-top box (switch the power off/on). Find instructions on how to restart the TV set-top box here.
In case of problems with the HDMI cable or the HDMI connections, the TV may lose the Swisscom TV signal for a short period of time. In this case, check the HDMI connection between the Swisscom TV set-top box and the TV, and try using another free HDMI input on the TV.