I have the same problem with mine. My 2 computers at home also have certificate issues but the one at the office works fine. All run the latest Opear browser and java7. At home I run Win7 and WinXP sp2 and at work win xp sp3.
One big difference is that I run Avira antivirus at home and we use Mcafee at the office. I have looked for system reguirements needed to run EPC but can't find anything. The forum is in german so that doesn't help either.

Attached is the error I receive.

Attached Thumbnails