vb.net external dos command hangs without returning output - vb.net

Question

I am running a dos command from my app, however the dos window just hangs without returning any output. It does work under Windows 8, but not Windows 7.
This is my code:
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
Dim process As New Process()
process.StartInfo.FileName = "C:\Program Files (x86)\Pico Technology\PicoScope6\picoscope.com"
process.StartInfo.UseShellExecute = False
process.StartInfo.Arguments = "/a Measurements.CSV?"
process.StartInfo.RedirectStandardInput = True
process.StartInfo.RedirectStandardOutput = True
process.Start()
Dim reader As StreamReader = process.StandardOutput
Dim output As String = reader.ReadToEnd()
RichTextBox1.Text = output
End Sub
picoscope.com is a 'wrapper' supplied by the PicoScope vendor - it appears to be a very small .net app, which calls the main PicoScope.exe program with some commands (unknown). The PicoScope.exe app needs to be running for this to work.
I wrote a small console app, and this works just fine - however I can't even call my console app from a forms based application.
Code for console app:
Sub Main()
Dim process As New Process()
process.StartInfo.FileName = "C:\Program Files (x86)\Pico Technology\PicoScope6\picoscope.com"
process.StartInfo.Arguments = "/a Measurements.CSV?"
process.StartInfo.UseShellExecute = False
process.StartInfo.RedirectStandardOutput = True
process.Start()
' Synchronously read the standard output of the spawned process.
Dim reader As StreamReader = process.StandardOutput
Dim output As String = reader.ReadToEnd()
process.WaitForExit()
process.Close()
End Sub
This seems to be some strange issue with Windows 7.
I can open cmd.exe without any issue, as well as spawn other applications.
It's almost as if there is some conflict between the running picoscope programs and my application.
Attempting to debug doesn't seem to help at all, with the exception of this:
A first chance exception of type 'System.InvalidOperationException' occurred in System.dll
I have tried several different approaches, disabling shell redirection, even trying to redirect the output to a file. But it would appear that anything to do with this Picoscope app just prevents it working.
I even tried writing another console app to redirect text output to the console and to a file and they worked (because the picoscope app wasn't involved!).
Likewise, a simple dos batch file with "echo Hello World" in it is successfully redirected to my forms app - so I'm sure my code is correct.
I am now at a loss as to what the issue could be here.
I'm using Visual Studio 2013, Windows 7 on SP1.
Can anyone offer any suggestions?
Apologies for the long post, I was trying to give as much detail as possible.
EDIT: Even more curious is that I tried my working app on another Windows 7 PC and it works...
I suspect this must be related to my specific Windows 7 PC (a fresh build).
I compared UAC settings with the other PC - they are the same.
Thanks.