I just maximised my bitminter client and nothing is showing in it except a picture of my windows desktop .
The client quickly becomes unresponsive and I have to close with task manager
A couple users reported running on block erupters locked up the whole client, then they reinstalled the drivers and the problem went away. Could you try that?
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx