I just noticed that Powershell complains about line 5 "At E:\vmw\Get-VmdkHeader.ps1:5 char:1" which is strange.
Do you by chance have some A/V, or endpoint security application, which injects code into scripts?

The first 6 lines should read:
# Extract Metadata from a single VMDK-File, or all VMDK-Files in a Directory
[CmdletBinding()]
Param(
[Parameter(Position=0)]
[String] $FilePath
)

André