VTeX support is broken and may be fixed by adding three \immediate statements in pgfsys-vtex.def (see attachment). This bug and fix has been known for a while
http://www.ntg.nl/pipermail/ntg-vtex/2007-March/000848.html
http://www.ntg.nl/pipermail/ntg-vtex/2007-March/000849.html,
but never ended up in the pgf package. It has been confirmed for VTeX/2 8.44 on OS/2, but should apply to all versions.
Also patterns do not work, probably caused by dynamic definition of /pgfpat#1 in \pgfsys@declarepattern.
The patch was included untested. Hopefully it is fixed.