Some bugs after update to 2.0.296

[peter@.....com]

Hi, I updated to Joomla 3.4.4 and OPC 2.0.296.090915 on my development server. I also use VM 3.0.9.

I get the following bugs, apparently related to the new OPC version.

blank productdetails page
but only when I'm not logged in (after login, the page shows normally)
when I disable OPC, the page shows normally

coupon problems on /cart page
gift voucher does not include shipping costs
when I delete an applied voucher and apply another voucher, the first (deleted) voucher is re-applied

You can check here:
http://dev.saintbasics.com

Can you pls. help out with fixing this? Thnx!
Peter