I've run into this too, and have others have said, there's no consistent way to "fix" this.

Every once in a while, I'll boot up one of my PCs and get the same triangle-in-the-icon problem. If I reboot the PC, that often goes away. Sometimes, I have to restart my router -- and then restart the PC -- and then it goes away. Sometimes, I have to restart the cable modem the router connects to, and then the router, and then the PC -- and it goes away.

IF there was a miracle cure, I'd love to have it and would gladly tell you about it.