Driver Provider: Arduino LLC (www.arduino.cc)
Driver Date: 1/1/2013
Driver Version: 1.0.0.0
Digital Signer: Arduino LLC
Device type: Ports (COM & LPT)
Manufacturer: Arduino LLC (www.arduino.cc)
Location: PORT_#0001.Hub_#0004
Windows 7 Professional, SP1.
I went into the event log and I found this error when trying to manually switch the arduino to COM4.
Faulting application name: mmc.exe, version: 6.1.7600.16385, time stamp: 0x4a5bc3f1
Faulting module name: MsPorts.dll, version: 6.1.7600.16385, time stamp: 0x4a5bc616
Exception code: 0xc0000005
Fault offset: 0x00006e87
Faulting process id: 0x12d8
Faulting application start time: 0x01ce24bc8918ccbc
Faulting application path: C:\Windows\system32\mmc.exe
Faulting module path: C:\Windows\system32\MsPorts.dll
Report Id: b53029e2-90b9-11e2-8f55-90fba6e581b8
maybe that will help. It is the latest lead I have to try and track something down.
Matt