pdf export issues - principally transparencies causing problems

[PeteA]

Hi - I've migrated from Freehand to Xara which we use as a tool to design scientific posters, mostly A0 in size. When exporting to a pdf for printing we've found the exporting of transparencies (and/or bevel effects) to be very hit and miss...

As a rule exporting for "email" distribution works fine. HOwever when we export as a high res pdf we get problems with bevels and transparencies not being correct in the pdf. This is particularly obvious when we have a lot of bevels or transparencies in the file. I've uploaded an example of one of our posters (authors removed for privacy) - exported as a emailable pdf is fine, but high res results in the top bar having a problem. I've uploaded the xara file but the pdfs are too big
Am i missing something obvious here - I've tried the different options (pdf 1.5, 1.6 etc) but it doesn't seem to make a difference. Bizzarlely at times when I slightly alter the misbehaving element and then re-export the pdf can come out fine!

thanks