Same problem: Crystal 10, exporting to PDF, error "Failed to export the report". Reported and reproduced on Windows 8.1. Our problem appears to be with Times New Roman and Arial fonts only. All other fonts tested so far worked fine. Problem observed with v6.88 of both of those fonts, included in KB3102429, installation of which definitely caused the problem. (I suppose it is possible it's not the font files causing the problem but some other file included in the update. I have not tested that.)
Previous v6.87 of both fonts worked fine. V6.90 of both fonts (Windows 10) also seem to work fine. We had a similar problem with TNR v6.85 (initial Windows 8.1 release) but it seems to have been fixed by v6.87.
KB3102429 has different versions of fonts for Windows 7. I have not yet tried to reproduce the problem on Windows 7 but I have seen reports that this update does cause a similar problem on Windows 7.
A workaround is to replace the TNR and Arial fonts in the report with other fonts, at design time or runtime. I can confirm that uninstalling KB3102429 reverted to v6.87 of both fonts and solved the problem for me.
See also this SAP forum. Peace.