I'm not seeing this problem myself, so you'll need to give me some more information. Are you using Chrome on a Mac, a PC, or something else? Have you installed GME directly as a native Chrome extension, or are you using Tampermonkey? If you disable GME, does the problem go away? Are there any error messages showing in the Chrome console (on the PC, you press Ctrl-Shift-J to see the console). Can you see GME's icons at the bottom-left of the map window?
Generally, if the map goes grey it means that there is a problem with your one of the map servers - perhaps the one that you use for your default map. If you select a different map, it may fix the problem. It can also happen if the map you are using doesn't have coverage of the area or zoom level you are looking at (e.g. MapQuest Ariel in most of Europe), or if your internet connection has gone down.
You can also try these trouble-shooting tips.
When i open the geocaching map it works for a short time, then everyting is grey and nothing is loading before i restart the browser.
Then it works for a very short time and then the same thing again