I've to produce multiple PDF for a customer and it seems, that PDF´s could not be opened. The PDF´s, that caused problems were those, produced with 9.04 Ghostscript.
I can´t uninstall the 9.04 because of missing admin-rights. I've now a "workaround".
If PDF creator starts to create PDF´s, it uses one of the two installed ghostscript versions for all created PDFs and did not change this. The used version I can query. If it doesn´t match 9.00 the procedure ends with a message. The user can manually change the version and restart. The change of the version seems to be saved within the userprofile of windows.