Permissions issue on shared volume

Hi, I have a second partition mounted as a RAW (Bootcamp) volume on the guest (Windows 2003 Server) which the host (10.6.4) has full access to. I keep all my data files on this volume. This has not been a problem until recently. Now the host has trouble reading/writing data to this volume which appears as a sort of permissions issue. In particular, when I try to compile a latex document (diss) on the shared volume using pdflatex I get a fatal error as if pdflatex cannot write to the disk:

(./diss.out) (./diss.outpdflatex: diss: Input/output error

Also, when running biber I get a similar error:

Cannot write to 'diss.blg': Input/output error at /opt/local/lib/perl5/site_perl/5.12.1/Log/Log4perl/Appender/File.pm line 245.

If I move the folder containing the relevant data files to the native Mac OS volume the document compiles without issue.

As I said, this is a new problem, even though I have been running Parallels (5 then 6) for a while now and performing these document compiles in the past without issue,

Any ideas?