Why does my game crash when I alt-tab out?

Based on your description, it seems like the game has issues when you switch away from it using alt-tab. That's not an uncommon issue, by the way -- I had it occur on several old casino games that didn't play well with others. In that case, you need to ensure your graphics card drivers are updated, and if you're playing from a browser, try switching browsers (Chrome/Firefox, etc). If you're playing from a desktop application, make sure you have the latest update. Some developers patch minor bugs and issues like this as they pop up. If none of that works, report the bug to the casino or the developer, they may have no idea players are having this issue.

Alt-tab crashes typically involve graphics or focus issues. Check if you can reduce the in-game resolution. Or try toggling the game between full screen and windowed modes using its options menu. If that doesn’t work, find the game’s config file and force windowed mode. Make sure you’ve installed all patches, because they may fix the crash. Older games require you to install them in compatibility mode, while others can benefit from graphics driver tweaks.

Alt-tab crashes: This is likely a problem with how the application responds to changes in window focus. The blackjack game you’re playing may have a bug. Try running it in a window rather than full-screen; it might be better at handling alt-tab. And make sure you have the latest graphics drivers installed. There are reports of similar problems on Reddit; they seem to suggest that switching to window mode and updating drivers helps. Alternatively, you can test other games from the wiki to ensure this isn’t a one-off issue.