On the GL1500 (the GL1800 also suffers from this problem) there are push-on/push-off buttons on the handlebars that control things like cruise control, hazard lights, and the audio mute. The shaft connecting the buttons to the actual switches are lubricated inside with a grease-like lubricant. This grease picks up dust and dirt over time until it is not lubricating anymore, and acts more as an adhesive than anything else.
It doesn't prevent you from pressing the button to turn it on. Where the problem arises is when you try to push the button again to turn it off - the tiny spring inside the switch is not powerful enough to push the button back out against the stiction of the dirty lubricant, and the button stays pushed in. As a result, you have Goldwing owners riding around with cruise control on, hazard lights flashing, and no music.
The solution is quick and simple. You will require some electrical contact cleaner. You want a quick-drying contact cleaner that does not leave residue behind. CRC Electrical Cleaner is my favorite:

I had originally found that WD-40 works quite well: its carrier flushes away the dirt on our switch mechanisms, and when it evaporates it leaves behind an oily film that lubricates it and keeps it working. However, I later found that the oily film attracts dust and dirt, meaning that the switches will begin sticking again a few months later - particularly in cold weather. I since switched to simple contact cleaner with great success.
1. The first switch is the easiest to do: The audio mute switch. The reason this one is easy is because no disassembly is required! Insert the cleaner straw into the right side of the tuning switch as shown, push it in until you feel the resistance of the mute switch mechanism, and spray. Give it a 1-2 second burst. If the switch is already stuck, start working it in and out until it pops free. Once it is free, give it another half-second spray, then work the switch in and out 10-20 times until it moves freely.

2. The hazard light switch requires that the left grip switch module be taken apart. There are two screws on the bottom that must be removed, as shown:

3. Once the screws are removed, the top half can be separated from the bottom half. You do not have to separate them completely - you just need access to the underside of the top half:

4. Insert the straw as shown, up and toward the mechanism of the hazard light switch. Lubricate it the same way as described for the Mute switch. Once it's working well, snap the halves back together and re-tighten the screws.

5. The cruise control switch on the right handgrip also has two screws on the bottom that must first be removed:

6. The cruise control switch mechanism is much more exposed and can be easily accessed and lubricated. Snap the halves back together and replace the screws.

It might not be a bad idea to put this item on your annual winter maintenance list. It only takes a few minutes to perform, and will prevent frustration down the road - literally - usually when you're miles from home!