ATmega 2560 win 7 SP1 driver issue

I've been working on this board successfully for some time using the 1.6.7 IDE.

Recently, when I plug in the usb connector, I hear the enumeration tone indicating board was detected then I hear the driver unload. When this happens I do not have the com port directory in control panel and the port selection in the 1.6.7 arduino IDE is greyed out.

After plugging and unplugging the board several times, once the com folder in control panel did come up indicating the board installed on com6, but within seconds it unloaded again and the com folder went away.

This is a relatively new machine with win7 sp1. In the past this has been very reliable on the driver.

I uninstalled and reinstalled the IDE, issue persisted.

any ideas how to recover previous reliable IDE operation?

thanks,
tim

Try a different USB port and a different USB cable.