Dead timekeeper batteries, leaking capacitors, broken disc trays and belts: CD-i players are not really future proof. Of course it's not just CD-i players, all retro electronics suffer from degradation in one way or another. One of the issues that occur a lot is the degradation of certain plastic coatings. Over time, these rubber coatings get sticky, very sticky. It's like the coating is dissolving into some kind of glue. What is happening here?
One of the victims of this is the CD-i carrying case. Philips offered a carrying case to take your portable CD-i player with you. This case has a rubber coating, but many of them got sticky nowadays. The coating is actually made of rubber which is kept in this 'hard' state by adding stabilizers. Over time, these stabilizers oxidize thanks to the oxygen in normal air. When the stabilizers lose their function of stabilizing the rubber, the rubber reverses back into its original state: Any material that will become rubber starts out life in a sticky condition: natural rubber comes from a rubber tree which emits a sticky syrup; synthetic rubber (probably what is used in this CD-i carrying case) comes from petroleum products. It is put through a vulcanizing process to make the material stretchy, not sticky. Stabilizers keep it that way.
So, that 'reversion' process of the rubber is (in many cases at least) due to the availability of oxygen. The stabilizers who keep the rubber as a 'hard' coating oxidize over time. There's not much you can do, if you want to preserve these products you should have a oxygen free space/area. Keeping it in a close bag helps (like those vacuum bags). But of course you should have done that before the reversion process even started. For now, there's nothing to reverse the rubber from getting sticky again (into syrup eventually), but those 'oxygen absorbers' and a close bag helps it from getting worse.
Another troubled product is the first version of the CD-i thumbstick, which was treated with exact the same coating!
[The pictures are courtesy of Retrostuff.org]