TortoiseHg extdiff problem

[Guy Coleman]

I'm running TortoiseHg 0.3 on Vista SP1 and having problems with
extdiff. It works fine when used without a revision, but whenever I add
a revision to compare to it aborts:

C:\Foo>hg vdiff -r 2770
abort: The process cannot access the file because it is being used by
another process:
c:\users\guy~1.col\appdata\local\temp\extdiff.jm_psa\Foo\bar.xml

This worked fine on the previous installation of 0.9.4 (from the "Python
Approach" installer) on a pre-SP1 Vista box. Any ideas?

Guy Coleman