Sam,
Replace /catalog/checkout_shipping.php from the MVS with your back up copy. I ran
into this problem to, but when I but in the back-up file it was working again.
There is a BUG somewhere in the MVS changes to /catalog/checkout_shipping.php. It
has to do with the UPSXML module and dimensions support.
I am going to take a look at the code and try and figure out what the BUG is. If any one
knows where the BUG is in this file please let me know.
For me this error occurs when MVS is turned off, because MVS does not support UPSXML
and dimensions support yet.
Charles