• I put the attached file in confluence
• I add this macro: {viewpdf:name=SemTech2010_PartII_JohanDeSmedt.pdf}
• The macro says: 'SemTech2010_PartII_JohanDeSmedt.pdf' is being converted. Please refresh after some time.
• I wait a couple of minutes, then refresh
• The macro says: "There was a problem converting this attachment. Please create an issue at http://jira.atlassian.com"

Another similar (even larger) attachment (SemTech2010_PartI_HenricStjernquist.pdf) shows up fine.
Sorry can't access the logs...