App crash with cryptic error code

I'm working on a C# application, but occasionally the GUI disappears (closes) without any warning. None of the exceptions catches seem to work, but I did notice the following error code in the VS output window:

The program '[5172] MyProg.vshost.exe: Managed (v4.0.30319)' has exited with code -2146233082 (0x80131506)

I would be grateful if someone could please decipher this error code, as it would point me in the right direction. I couldn't find it in Microsoft's standard error code table.. Thanks.