Current Working Directory of Startup Program

I created a startup program by putting a registry entry in:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

Name="my program"
Type=string
Value="C:\some\directory\myProgram.exe"

This program opens a file in the Current Working Directory - say file
C:\some\directory\someFile.txt

When windows starts, it runs "C:\some\directory\myProgram.exe" and
cannot find "C:\some\directory\someFile.txt", I'm guessing because the
when it's executing this command it is from another directory. What
is the current working directory when Windows fires startup commands?
I tried copy "someFile.txt" to c:\windows\system32 with no luck.

Thanks