What is this?

[NickBullard]

Can you post up your Launch Log file UDK-20XX-XX/UDKGame/Logs/...

[Spoondog]

weird... maybe a file got corrupted somehow. try reinstalling UDK and transfer your content into the new installation?

[quytin1992]

Before blaming on UDK, I'd like to clear out that I have not touched anything relates to UDK config or scripts since I downloaded the latest version.

I'm an artist, so all I do is building my scene. Everything worked just fine yesterday, but when I start UDK this morning, it threw a error onto my screen. It said:
"MaterialExpressionTextureParameterSubUV.uc: unknown macro = none". What is going on here? I hope that it didn't kill any of my work. Anyone has the same problem?