Short answer, close idle-master then restart steam to avoid vac error.

See the pinned discussions thread.

Does task manager say idlemaster.exe is running?
Steam now says you're playing left 4 dead 2.

Just clicked your profile, it doesn't say you're playing anything.

Screenshot

http://psteamcommunity.yuanyoumao.com/my/badges

Not a very helpful screenshot. Either you don't have card drops left or your account is restricted because steam requires it be funded or game bought off steam store.


Idle master reads your badge page, linked here, it looks for 'card drops remaining'
http://psteamcommunity.yuanyoumao.com/my/badges

Steam gives the cards(not idle master), Steam only gives half a badge set number of cards.
http://psteamcommunity.yuanyoumao.com/tradingcards/faq

You need to buy the rest or trade for them:
http://psteamcommunity.yuanyoumao.com/market/

Free-to-play games do not drop cards unless you spend lots of $€£ on in-game purchases or DLCs

It's working.

Idle master reads your badge page, linked here, it looks for 'card drops remaining'
http://psteamcommunity.yuanyoumao.com/my/badges

Steam gives the cards(not idle master), Steam only gives half a badge set number of cards.
http://psteamcommunity.yuanyoumao.com/tradingcards/faq

You need to buy the rest or trade for them:
http://psteamcommunity.yuanyoumao.com/market/

Free-to-play games do not drop cards unless you spend lots of $€£ on in-game purchases or DLCs

Steam drops 1/2 a badge set for any applicable games in your library that are played.

No, the program stops working when you close it. You don't lose anything at all because all Idle-master does is say to steam that game xyz is running. When you close idle-master, the hey-steam-this-game-is-running-notice stops too.