get-ciminstance "Cannot create a file when that file already exists"

Just installed PowerShell 5 on my W7SP1 box. Wanted to use it to examine installed programs. Tried:

    get-ciminstance -ClassName Win32_InstalledWin32Program

That worked but unsurprisingly gave a long list with a lot of information that I didn't need, so I tried to narrow it down.

Tried:

    get-ciminstance -ClassName Win32_InstalledWin32Program | get-object name

and that gave an error because (being very new to PowerShell) I had tried get-object whereas it should have been select-object.

So I tried again, this time using select-object and got:

get-ciminstance : Cannot create a file when that file already exists.
At line:1 char:10
+ $progs = get-ciminstance -ClassName Win32_InstalledWin32Program
+          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ResourceExists: (root\cimv2:Win32_InstalledWin32Program:String) [Get-CimInstance], CimEx
   ception
    + FullyQualifiedErrorId : HRESULT 0x800700b7,Microsoft.Management.Infrastructure.CimCmdlets.GetCimInstanceCommand

Any time I try using get-ciminstance -classname I get this same error now.

Tried using procmon pointing at the PowerShell process to see what was happening but the only file access I could see was it reading DLLs.

Totally confused. Anyone know what the problem is or have any suggestions as to how to analyse?